| /* |
| * |
| * Copyright 2016 gRPC authors. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| */ |
| |
| #include "src/core/lib/iomgr/port.h" |
| |
| #include <grpc/grpc_posix.h> |
| #include <grpc/support/log.h> |
| |
| /* This polling engine is only relevant on linux kernels supporting epoll() */ |
| #ifdef GRPC_LINUX_EPOLL |
| |
| #include "src/core/lib/iomgr/ev_epollsig_linux.h" |
| |
| #include <assert.h> |
| #include <errno.h> |
| #include <limits.h> |
| #include <poll.h> |
| #include <pthread.h> |
| #include <signal.h> |
| #include <string.h> |
| #include <sys/epoll.h> |
| #include <sys/socket.h> |
| #include <unistd.h> |
| |
| #include <grpc/support/alloc.h> |
| #include <grpc/support/string_util.h> |
| #include <grpc/support/tls.h> |
| #include <grpc/support/useful.h> |
| |
| #include "src/core/lib/debug/stats.h" |
| #include "src/core/lib/iomgr/block_annotate.h" |
| #include "src/core/lib/iomgr/ev_posix.h" |
| #include "src/core/lib/iomgr/iomgr_internal.h" |
| #include "src/core/lib/iomgr/lockfree_event.h" |
| #include "src/core/lib/iomgr/timer.h" |
| #include "src/core/lib/iomgr/wakeup_fd_posix.h" |
| #include "src/core/lib/profiling/timers.h" |
| #include "src/core/lib/support/manual_constructor.h" |
| |
| #define GRPC_POLLSET_KICK_BROADCAST ((grpc_pollset_worker*)1) |
| |
| #define GRPC_POLLING_TRACE(...) \ |
| if (grpc_polling_trace.enabled()) { \ |
| gpr_log(GPR_INFO, __VA_ARGS__); \ |
| } |
| |
| static int grpc_wakeup_signal = -1; |
| static bool is_grpc_wakeup_signal_initialized = false; |
| |
| /* Implements the function defined in grpc_posix.h. This function might be |
| * called before even calling grpc_init() to set either a different signal to |
| * use. If signum == -1, then the use of signals is disabled */ |
| void grpc_use_signal(int signum) { |
| grpc_wakeup_signal = signum; |
| is_grpc_wakeup_signal_initialized = true; |
| |
| if (grpc_wakeup_signal < 0) { |
| gpr_log(GPR_INFO, |
| "Use of signals is disabled. Epoll engine will not be used"); |
| } else { |
| gpr_log(GPR_INFO, "epoll engine will be using signal: %d", |
| grpc_wakeup_signal); |
| } |
| } |
| |
| struct polling_island; |
| |
| typedef enum { |
| POLL_OBJ_FD, |
| POLL_OBJ_POLLSET, |
| POLL_OBJ_POLLSET_SET |
| } poll_obj_type; |
| |
| typedef struct poll_obj { |
| #ifndef NDEBUG |
| poll_obj_type obj_type; |
| #endif |
| gpr_mu mu; |
| struct polling_island* pi; |
| } poll_obj; |
| |
| const char* poll_obj_string(poll_obj_type po_type) { |
| switch (po_type) { |
| case POLL_OBJ_FD: |
| return "fd"; |
| case POLL_OBJ_POLLSET: |
| return "pollset"; |
| case POLL_OBJ_POLLSET_SET: |
| return "pollset_set"; |
| } |
| |
| GPR_UNREACHABLE_CODE(return "UNKNOWN"); |
| } |
| |
| /******************************************************************************* |
| * Fd Declarations |
| */ |
| |
| #define FD_FROM_PO(po) ((grpc_fd*)(po)) |
| |
| struct grpc_fd { |
| poll_obj po; |
| |
| int fd; |
| /* refst format: |
| bit 0 : 1=Active / 0=Orphaned |
| bits 1-n : refcount |
| Ref/Unref by two to avoid altering the orphaned bit */ |
| gpr_atm refst; |
| |
| /* The fd is either closed or we relinquished control of it. In either |
| cases, this indicates that the 'fd' on this structure is no longer |
| valid */ |
| bool orphaned; |
| |
| grpc_core::ManualConstructor<grpc_core::LockfreeEvent> read_closure; |
| grpc_core::ManualConstructor<grpc_core::LockfreeEvent> write_closure; |
| |
| struct grpc_fd* freelist_next; |
| grpc_closure* on_done_closure; |
| |
| /* The pollset that last noticed that the fd is readable. The actual type |
| * stored in this is (grpc_pollset *) */ |
| gpr_atm read_notifier_pollset; |
| |
| grpc_iomgr_object iomgr_object; |
| }; |
| |
| /* Reference counting for fds */ |
| #ifndef NDEBUG |
| static void fd_ref(grpc_fd* fd, const char* reason, const char* file, int line); |
| static void fd_unref(grpc_fd* fd, const char* reason, const char* file, |
| int line); |
| #define GRPC_FD_REF(fd, reason) fd_ref(fd, reason, __FILE__, __LINE__) |
| #define GRPC_FD_UNREF(fd, reason) fd_unref(fd, reason, __FILE__, __LINE__) |
| #else |
| static void fd_ref(grpc_fd* fd); |
| static void fd_unref(grpc_fd* fd); |
| #define GRPC_FD_REF(fd, reason) fd_ref(fd) |
| #define GRPC_FD_UNREF(fd, reason) fd_unref(fd) |
| #endif |
| |
| static void fd_global_init(void); |
| static void fd_global_shutdown(void); |
| |
| /******************************************************************************* |
| * Polling island Declarations |
| */ |
| |
| #ifndef NDEBUG |
| |
| #define PI_ADD_REF(p, r) pi_add_ref_dbg((p), (r), __FILE__, __LINE__) |
| #define PI_UNREF(p, r) pi_unref_dbg((p), (r), __FILE__, __LINE__) |
| |
| #else |
| |
| #define PI_ADD_REF(p, r) pi_add_ref((p)) |
| #define PI_UNREF(p, r) pi_unref((p)) |
| |
| #endif |
| |
| /* This is also used as grpc_workqueue (by directly casing it) */ |
| typedef struct polling_island { |
| gpr_mu mu; |
| /* Ref count. Use PI_ADD_REF() and PI_UNREF() macros to increment/decrement |
| the refcount. |
| Once the ref count becomes zero, this structure is destroyed which means |
| we should ensure that there is never a scenario where a PI_ADD_REF() is |
| racing with a PI_UNREF() that just made the ref_count zero. */ |
| gpr_atm ref_count; |
| |
| /* Pointer to the polling_island this merged into. |
| * merged_to value is only set once in polling_island's lifetime (and that too |
| * only if the island is merged with another island). Because of this, we can |
| * use gpr_atm type here so that we can do atomic access on this and reduce |
| * lock contention on 'mu' mutex. |
| * |
| * Note that if this field is not NULL (i.e not 0), all the remaining fields |
| * (except mu and ref_count) are invalid and must be ignored. */ |
| gpr_atm merged_to; |
| |
| /* Number of threads currently polling on this island */ |
| gpr_atm poller_count; |
| |
| /* The fd of the underlying epoll set */ |
| int epoll_fd; |
| |
| /* The file descriptors in the epoll set */ |
| size_t fd_cnt; |
| size_t fd_capacity; |
| grpc_fd** fds; |
| } polling_island; |
| |
| /******************************************************************************* |
| * Pollset Declarations |
| */ |
| struct grpc_pollset_worker { |
| /* Thread id of this worker */ |
| pthread_t pt_id; |
| |
| /* Used to prevent a worker from getting kicked multiple times */ |
| gpr_atm is_kicked; |
| struct grpc_pollset_worker* next; |
| struct grpc_pollset_worker* prev; |
| }; |
| |
| struct grpc_pollset { |
| poll_obj po; |
| |
| grpc_pollset_worker root_worker; |
| bool kicked_without_pollers; |
| |
| bool shutting_down; /* Is the pollset shutting down ? */ |
| bool finish_shutdown_called; /* Is the 'finish_shutdown_locked()' called ? */ |
| grpc_closure* shutdown_done; /* Called after after shutdown is complete */ |
| }; |
| |
| /******************************************************************************* |
| * Pollset-set Declarations |
| */ |
| struct grpc_pollset_set { |
| poll_obj po; |
| }; |
| |
| /******************************************************************************* |
| * Common helpers |
| */ |
| |
| static bool append_error(grpc_error** composite, grpc_error* error, |
| const char* desc) { |
| if (error == GRPC_ERROR_NONE) return true; |
| if (*composite == GRPC_ERROR_NONE) { |
| *composite = GRPC_ERROR_CREATE_FROM_COPIED_STRING(desc); |
| } |
| *composite = grpc_error_add_child(*composite, error); |
| return false; |
| } |
| |
| /******************************************************************************* |
| * Polling island Definitions |
| */ |
| |
| /* The wakeup fd that is used to wake up all threads in a Polling island. This |
| is useful in the polling island merge operation where we need to wakeup all |
| the threads currently polling the smaller polling island (so that they can |
| start polling the new/merged polling island) |
| |
| NOTE: This fd is initialized to be readable and MUST NOT be consumed i.e the |
| threads that woke up MUST NOT call grpc_wakeup_fd_consume_wakeup() */ |
| static grpc_wakeup_fd polling_island_wakeup_fd; |
| |
| /* The polling island being polled right now. |
| See comments in workqueue_maybe_wakeup for why this is tracked. */ |
| static __thread polling_island* g_current_thread_polling_island; |
| |
| /* Forward declaration */ |
| static void polling_island_delete(polling_island* pi); |
| |
| #ifdef GRPC_TSAN |
| /* Currently TSAN may incorrectly flag data races between epoll_ctl and |
| epoll_wait for any grpc_fd structs that are added to the epoll set via |
| epoll_ctl and are returned (within a very short window) via epoll_wait(). |
| |
| To work-around this race, we establish a happens-before relation between |
| the code just-before epoll_ctl() and the code after epoll_wait() by using |
| this atomic */ |
| gpr_atm g_epoll_sync; |
| #endif /* defined(GRPC_TSAN) */ |
| |
| static void pi_add_ref(polling_island* pi); |
| static void pi_unref(polling_island* pi); |
| |
| #ifndef NDEBUG |
| static void pi_add_ref_dbg(polling_island* pi, const char* reason, |
| const char* file, int line) { |
| if (grpc_polling_trace.enabled()) { |
| gpr_atm old_cnt = gpr_atm_acq_load(&pi->ref_count); |
| gpr_log(GPR_DEBUG, |
| "Add ref pi: %p, old:%" PRIdPTR " -> new:%" PRIdPTR |
| " (%s) - (%s, %d)", |
| pi, old_cnt, old_cnt + 1, reason, file, line); |
| } |
| pi_add_ref(pi); |
| } |
| |
| static void pi_unref_dbg(polling_island* pi, const char* reason, |
| const char* file, int line) { |
| if (grpc_polling_trace.enabled()) { |
| gpr_atm old_cnt = gpr_atm_acq_load(&pi->ref_count); |
| gpr_log(GPR_DEBUG, |
| "Unref pi: %p, old:%" PRIdPTR " -> new:%" PRIdPTR |
| " (%s) - (%s, %d)", |
| pi, old_cnt, (old_cnt - 1), reason, file, line); |
| } |
| pi_unref(pi); |
| } |
| #endif |
| |
| static void pi_add_ref(polling_island* pi) { |
| gpr_atm_no_barrier_fetch_add(&pi->ref_count, 1); |
| } |
| |
| static void pi_unref(polling_island* pi) { |
| /* If ref count went to zero, delete the polling island. |
| Note that this deletion not be done under a lock. Once the ref count goes |
| to zero, we are guaranteed that no one else holds a reference to the |
| polling island (and that there is no racing pi_add_ref() call either). |
| |
| Also, if we are deleting the polling island and the merged_to field is |
| non-empty, we should remove a ref to the merged_to polling island |
| */ |
| if (1 == gpr_atm_full_fetch_add(&pi->ref_count, -1)) { |
| polling_island* next = (polling_island*)gpr_atm_acq_load(&pi->merged_to); |
| polling_island_delete(pi); |
| if (next != nullptr) { |
| PI_UNREF(next, "pi_delete"); /* Recursive call */ |
| } |
| } |
| } |
| |
| /* The caller is expected to hold pi->mu lock before calling this function */ |
| static void polling_island_add_fds_locked(polling_island* pi, grpc_fd** fds, |
| size_t fd_count, bool add_fd_refs, |
| grpc_error** error) { |
| int err; |
| size_t i; |
| struct epoll_event ev; |
| char* err_msg; |
| const char* err_desc = "polling_island_add_fds"; |
| |
| #ifdef GRPC_TSAN |
| /* See the definition of g_epoll_sync for more context */ |
| gpr_atm_rel_store(&g_epoll_sync, (gpr_atm)0); |
| #endif /* defined(GRPC_TSAN) */ |
| |
| for (i = 0; i < fd_count; i++) { |
| ev.events = (uint32_t)(EPOLLIN | EPOLLOUT | EPOLLET); |
| ev.data.ptr = fds[i]; |
| err = epoll_ctl(pi->epoll_fd, EPOLL_CTL_ADD, fds[i]->fd, &ev); |
| |
| if (err < 0) { |
| if (errno != EEXIST) { |
| gpr_asprintf( |
| &err_msg, |
| "epoll_ctl (epoll_fd: %d) add fd: %d failed with error: %d (%s)", |
| pi->epoll_fd, fds[i]->fd, errno, strerror(errno)); |
| append_error(error, GRPC_OS_ERROR(errno, err_msg), err_desc); |
| gpr_free(err_msg); |
| } |
| |
| continue; |
| } |
| |
| if (pi->fd_cnt == pi->fd_capacity) { |
| pi->fd_capacity = GPR_MAX(pi->fd_capacity + 8, pi->fd_cnt * 3 / 2); |
| pi->fds = |
| (grpc_fd**)gpr_realloc(pi->fds, sizeof(grpc_fd*) * pi->fd_capacity); |
| } |
| |
| pi->fds[pi->fd_cnt++] = fds[i]; |
| if (add_fd_refs) { |
| GRPC_FD_REF(fds[i], "polling_island"); |
| } |
| } |
| } |
| |
| /* The caller is expected to hold pi->mu before calling this */ |
| static void polling_island_add_wakeup_fd_locked(polling_island* pi, |
| grpc_wakeup_fd* wakeup_fd, |
| grpc_error** error) { |
| struct epoll_event ev; |
| int err; |
| char* err_msg; |
| const char* err_desc = "polling_island_add_wakeup_fd"; |
| |
| ev.events = (uint32_t)(EPOLLIN | EPOLLET); |
| ev.data.ptr = wakeup_fd; |
| err = epoll_ctl(pi->epoll_fd, EPOLL_CTL_ADD, |
| GRPC_WAKEUP_FD_GET_READ_FD(wakeup_fd), &ev); |
| if (err < 0 && errno != EEXIST) { |
| gpr_asprintf(&err_msg, |
| "epoll_ctl (epoll_fd: %d) add wakeup fd: %d failed with " |
| "error: %d (%s)", |
| pi->epoll_fd, GRPC_WAKEUP_FD_GET_READ_FD(wakeup_fd), errno, |
| strerror(errno)); |
| append_error(error, GRPC_OS_ERROR(errno, err_msg), err_desc); |
| gpr_free(err_msg); |
| } |
| } |
| |
| /* The caller is expected to hold pi->mu lock before calling this function */ |
| static void polling_island_remove_all_fds_locked(polling_island* pi, |
| bool remove_fd_refs, |
| grpc_error** error) { |
| int err; |
| size_t i; |
| char* err_msg; |
| const char* err_desc = "polling_island_remove_fds"; |
| |
| for (i = 0; i < pi->fd_cnt; i++) { |
| err = epoll_ctl(pi->epoll_fd, EPOLL_CTL_DEL, pi->fds[i]->fd, nullptr); |
| if (err < 0 && errno != ENOENT) { |
| gpr_asprintf(&err_msg, |
| "epoll_ctl (epoll_fd: %d) delete fds[%zu]: %d failed with " |
| "error: %d (%s)", |
| pi->epoll_fd, i, pi->fds[i]->fd, errno, strerror(errno)); |
| append_error(error, GRPC_OS_ERROR(errno, err_msg), err_desc); |
| gpr_free(err_msg); |
| } |
| |
| if (remove_fd_refs) { |
| GRPC_FD_UNREF(pi->fds[i], "polling_island"); |
| } |
| } |
| |
| pi->fd_cnt = 0; |
| } |
| |
| /* The caller is expected to hold pi->mu lock before calling this function */ |
| static void polling_island_remove_fd_locked(polling_island* pi, grpc_fd* fd, |
| bool is_fd_closed, |
| grpc_error** error) { |
| int err; |
| size_t i; |
| char* err_msg; |
| const char* err_desc = "polling_island_remove_fd"; |
| |
| /* If fd is already closed, then it would have been automatically been removed |
| from the epoll set */ |
| if (!is_fd_closed) { |
| err = epoll_ctl(pi->epoll_fd, EPOLL_CTL_DEL, fd->fd, nullptr); |
| if (err < 0 && errno != ENOENT) { |
| gpr_asprintf( |
| &err_msg, |
| "epoll_ctl (epoll_fd: %d) del fd: %d failed with error: %d (%s)", |
| pi->epoll_fd, fd->fd, errno, strerror(errno)); |
| append_error(error, GRPC_OS_ERROR(errno, err_msg), err_desc); |
| gpr_free(err_msg); |
| } |
| } |
| |
| for (i = 0; i < pi->fd_cnt; i++) { |
| if (pi->fds[i] == fd) { |
| pi->fds[i] = pi->fds[--pi->fd_cnt]; |
| GRPC_FD_UNREF(fd, "polling_island"); |
| break; |
| } |
| } |
| } |
| |
| /* Might return NULL in case of an error */ |
| static polling_island* polling_island_create(grpc_fd* initial_fd, |
| grpc_error** error) { |
| polling_island* pi = nullptr; |
| const char* err_desc = "polling_island_create"; |
| |
| *error = GRPC_ERROR_NONE; |
| |
| pi = (polling_island*)gpr_malloc(sizeof(*pi)); |
| gpr_mu_init(&pi->mu); |
| pi->fd_cnt = 0; |
| pi->fd_capacity = 0; |
| pi->fds = nullptr; |
| pi->epoll_fd = -1; |
| |
| gpr_atm_rel_store(&pi->ref_count, 0); |
| gpr_atm_rel_store(&pi->poller_count, 0); |
| gpr_atm_rel_store(&pi->merged_to, (gpr_atm) nullptr); |
| |
| pi->epoll_fd = epoll_create1(EPOLL_CLOEXEC); |
| |
| if (pi->epoll_fd < 0) { |
| append_error(error, GRPC_OS_ERROR(errno, "epoll_create1"), err_desc); |
| goto done; |
| } |
| |
| if (initial_fd != nullptr) { |
| polling_island_add_fds_locked(pi, &initial_fd, 1, true, error); |
| } |
| |
| done: |
| if (*error != GRPC_ERROR_NONE) { |
| polling_island_delete(pi); |
| pi = nullptr; |
| } |
| return pi; |
| } |
| |
| static void polling_island_delete(polling_island* pi) { |
| GPR_ASSERT(pi->fd_cnt == 0); |
| |
| if (pi->epoll_fd >= 0) { |
| close(pi->epoll_fd); |
| } |
| gpr_mu_destroy(&pi->mu); |
| gpr_free(pi->fds); |
| gpr_free(pi); |
| } |
| |
| /* Attempts to gets the last polling island in the linked list (liked by the |
| * 'merged_to' field). Since this does not lock the polling island, there are no |
| * guarantees that the island returned is the last island */ |
| static polling_island* polling_island_maybe_get_latest(polling_island* pi) { |
| polling_island* next = (polling_island*)gpr_atm_acq_load(&pi->merged_to); |
| while (next != nullptr) { |
| pi = next; |
| next = (polling_island*)gpr_atm_acq_load(&pi->merged_to); |
| } |
| |
| return pi; |
| } |
| |
| /* Gets the lock on the *latest* polling island i.e the last polling island in |
| the linked list (linked by the 'merged_to' field). Call gpr_mu_unlock on the |
| returned polling island's mu. |
| Usage: To lock/unlock polling island "pi", do the following: |
| polling_island *pi_latest = polling_island_lock(pi); |
| ... |
| ... critical section .. |
| ... |
| gpr_mu_unlock(&pi_latest->mu); // NOTE: use pi_latest->mu. NOT pi->mu */ |
| static polling_island* polling_island_lock(polling_island* pi) { |
| polling_island* next = nullptr; |
| |
| while (true) { |
| next = (polling_island*)gpr_atm_acq_load(&pi->merged_to); |
| if (next == nullptr) { |
| /* Looks like 'pi' is the last node in the linked list but unless we check |
| this by holding the pi->mu lock, we cannot be sure (i.e without the |
| pi->mu lock, we don't prevent island merges). |
| To be absolutely sure, check once more by holding the pi->mu lock */ |
| gpr_mu_lock(&pi->mu); |
| next = (polling_island*)gpr_atm_acq_load(&pi->merged_to); |
| if (next == nullptr) { |
| /* pi is infact the last node and we have the pi->mu lock. we're done */ |
| break; |
| } |
| |
| /* pi->merged_to is not NULL i.e pi isn't the last node anymore. pi->mu |
| * isn't the lock we are interested in. Continue traversing the list */ |
| gpr_mu_unlock(&pi->mu); |
| } |
| |
| pi = next; |
| } |
| |
| return pi; |
| } |
| |
| /* Gets the lock on the *latest* polling islands in the linked lists pointed by |
| *p and *q (and also updates *p and *q to point to the latest polling islands) |
| |
| This function is needed because calling the following block of code to obtain |
| locks on polling islands (*p and *q) is prone to deadlocks. |
| { |
| polling_island_lock(*p, true); |
| polling_island_lock(*q, true); |
| } |
| |
| Usage/example: |
| polling_island *p1; |
| polling_island *p2; |
| .. |
| polling_island_lock_pair(&p1, &p2); |
| .. |
| .. Critical section with both p1 and p2 locked |
| .. |
| // Release locks: Always call polling_island_unlock_pair() to release locks |
| polling_island_unlock_pair(p1, p2); |
| */ |
| static void polling_island_lock_pair(polling_island** p, polling_island** q) { |
| polling_island* pi_1 = *p; |
| polling_island* pi_2 = *q; |
| polling_island* next_1 = nullptr; |
| polling_island* next_2 = nullptr; |
| |
| /* The algorithm is simple: |
| - Go to the last polling islands in the linked lists *pi_1 and *pi_2 (and |
| keep updating pi_1 and pi_2) |
| - Then obtain locks on the islands by following a lock order rule of |
| locking polling_island with lower address first |
| Special case: Before obtaining the locks, check if pi_1 and pi_2 are |
| pointing to the same island. If that is the case, we can just call |
| polling_island_lock() |
| - After obtaining both the locks, double check that the polling islands |
| are still the last polling islands in their respective linked lists |
| (this is because there might have been polling island merges before |
| we got the lock) |
| - If the polling islands are the last islands, we are done. If not, |
| release the locks and continue the process from the first step */ |
| while (true) { |
| next_1 = (polling_island*)gpr_atm_acq_load(&pi_1->merged_to); |
| while (next_1 != nullptr) { |
| pi_1 = next_1; |
| next_1 = (polling_island*)gpr_atm_acq_load(&pi_1->merged_to); |
| } |
| |
| next_2 = (polling_island*)gpr_atm_acq_load(&pi_2->merged_to); |
| while (next_2 != nullptr) { |
| pi_2 = next_2; |
| next_2 = (polling_island*)gpr_atm_acq_load(&pi_2->merged_to); |
| } |
| |
| if (pi_1 == pi_2) { |
| pi_1 = pi_2 = polling_island_lock(pi_1); |
| break; |
| } |
| |
| if (pi_1 < pi_2) { |
| gpr_mu_lock(&pi_1->mu); |
| gpr_mu_lock(&pi_2->mu); |
| } else { |
| gpr_mu_lock(&pi_2->mu); |
| gpr_mu_lock(&pi_1->mu); |
| } |
| |
| next_1 = (polling_island*)gpr_atm_acq_load(&pi_1->merged_to); |
| next_2 = (polling_island*)gpr_atm_acq_load(&pi_2->merged_to); |
| if (next_1 == nullptr && next_2 == nullptr) { |
| break; |
| } |
| |
| gpr_mu_unlock(&pi_1->mu); |
| gpr_mu_unlock(&pi_2->mu); |
| } |
| |
| *p = pi_1; |
| *q = pi_2; |
| } |
| |
| static void polling_island_unlock_pair(polling_island* p, polling_island* q) { |
| if (p == q) { |
| gpr_mu_unlock(&p->mu); |
| } else { |
| gpr_mu_unlock(&p->mu); |
| gpr_mu_unlock(&q->mu); |
| } |
| } |
| |
| static polling_island* polling_island_merge(polling_island* p, |
| polling_island* q, |
| grpc_error** error) { |
| /* Get locks on both the polling islands */ |
| polling_island_lock_pair(&p, &q); |
| |
| if (p != q) { |
| /* Make sure that p points to the polling island with fewer fds than q */ |
| if (p->fd_cnt > q->fd_cnt) { |
| GPR_SWAP(polling_island*, p, q); |
| } |
| |
| /* Merge p with q i.e move all the fds from p (The one with fewer fds) to q |
| Note that the refcounts on the fds being moved will not change here. |
| This is why the last param in the following two functions is 'false') */ |
| polling_island_add_fds_locked(q, p->fds, p->fd_cnt, false, error); |
| polling_island_remove_all_fds_locked(p, false, error); |
| |
| /* Wakeup all the pollers (if any) on p so that they pickup this change */ |
| polling_island_add_wakeup_fd_locked(p, &polling_island_wakeup_fd, error); |
| |
| /* Add the 'merged_to' link from p --> q */ |
| gpr_atm_rel_store(&p->merged_to, (gpr_atm)q); |
| PI_ADD_REF(q, "pi_merge"); /* To account for the new incoming ref from p */ |
| } |
| /* else if p == q, nothing needs to be done */ |
| |
| polling_island_unlock_pair(p, q); |
| |
| /* Return the merged polling island (Note that no merge would have happened |
| if p == q which is ok) */ |
| return q; |
| } |
| |
| static grpc_error* polling_island_global_init() { |
| grpc_error* error = GRPC_ERROR_NONE; |
| |
| error = grpc_wakeup_fd_init(&polling_island_wakeup_fd); |
| if (error == GRPC_ERROR_NONE) { |
| error = grpc_wakeup_fd_wakeup(&polling_island_wakeup_fd); |
| } |
| |
| return error; |
| } |
| |
| static void polling_island_global_shutdown() { |
| grpc_wakeup_fd_destroy(&polling_island_wakeup_fd); |
| } |
| |
| /******************************************************************************* |
| * Fd Definitions |
| */ |
| |
| /* We need to keep a freelist not because of any concerns of malloc performance |
| * but instead so that implementations with multiple threads in (for example) |
| * epoll_wait deal with the race between pollset removal and incoming poll |
| * notifications. |
| * |
| * The problem is that the poller ultimately holds a reference to this |
| * object, so it is very difficult to know when is safe to free it, at least |
| * without some expensive synchronization. |
| * |
| * If we keep the object freelisted, in the worst case losing this race just |
| * becomes a spurious read notification on a reused fd. |
| */ |
| |
| /* The alarm system needs to be able to wakeup 'some poller' sometimes |
| * (specifically when a new alarm needs to be triggered earlier than the next |
| * alarm 'epoch'). This wakeup_fd gives us something to alert on when such a |
| * case occurs. */ |
| |
| static grpc_fd* fd_freelist = nullptr; |
| static gpr_mu fd_freelist_mu; |
| |
| #ifndef NDEBUG |
| #define REF_BY(fd, n, reason) ref_by(fd, n, reason, __FILE__, __LINE__) |
| #define UNREF_BY(fd, n, reason) unref_by(fd, n, reason, __FILE__, __LINE__) |
| static void ref_by(grpc_fd* fd, int n, const char* reason, const char* file, |
| int line) { |
| if (grpc_trace_fd_refcount.enabled()) { |
| gpr_log(GPR_DEBUG, |
| "FD %d %p ref %d %" PRIdPTR " -> %" PRIdPTR " [%s; %s:%d]", |
| fd->fd, fd, n, gpr_atm_no_barrier_load(&fd->refst), |
| gpr_atm_no_barrier_load(&fd->refst) + n, reason, file, line); |
| } |
| #else |
| #define REF_BY(fd, n, reason) ref_by(fd, n) |
| #define UNREF_BY(fd, n, reason) unref_by(fd, n) |
| static void ref_by(grpc_fd* fd, int n) { |
| #endif |
| GPR_ASSERT(gpr_atm_no_barrier_fetch_add(&fd->refst, n) > 0); |
| } |
| |
| #ifndef NDEBUG |
| static void unref_by(grpc_fd* fd, int n, const char* reason, const char* file, |
| int line) { |
| if (grpc_trace_fd_refcount.enabled()) { |
| gpr_log(GPR_DEBUG, |
| "FD %d %p unref %d %" PRIdPTR " -> %" PRIdPTR " [%s; %s:%d]", |
| fd->fd, fd, n, gpr_atm_no_barrier_load(&fd->refst), |
| gpr_atm_no_barrier_load(&fd->refst) - n, reason, file, line); |
| } |
| #else |
| static void unref_by(grpc_fd* fd, int n) { |
| #endif |
| gpr_atm old = gpr_atm_full_fetch_add(&fd->refst, -n); |
| if (old == n) { |
| /* Add the fd to the freelist */ |
| gpr_mu_lock(&fd_freelist_mu); |
| fd->freelist_next = fd_freelist; |
| fd_freelist = fd; |
| grpc_iomgr_unregister_object(&fd->iomgr_object); |
| |
| fd->read_closure->DestroyEvent(); |
| fd->write_closure->DestroyEvent(); |
| |
| gpr_mu_unlock(&fd_freelist_mu); |
| } else { |
| GPR_ASSERT(old > n); |
| } |
| } |
| |
| /* Increment refcount by two to avoid changing the orphan bit */ |
| #ifndef NDEBUG |
| static void fd_ref(grpc_fd* fd, const char* reason, const char* file, |
| int line) { |
| ref_by(fd, 2, reason, file, line); |
| } |
| |
| static void fd_unref(grpc_fd* fd, const char* reason, const char* file, |
| int line) { |
| unref_by(fd, 2, reason, file, line); |
| } |
| #else |
| static void fd_ref(grpc_fd* fd) { ref_by(fd, 2); } |
| static void fd_unref(grpc_fd* fd) { unref_by(fd, 2); } |
| #endif |
| |
| static void fd_global_init(void) { gpr_mu_init(&fd_freelist_mu); } |
| |
| static void fd_global_shutdown(void) { |
| gpr_mu_lock(&fd_freelist_mu); |
| gpr_mu_unlock(&fd_freelist_mu); |
| while (fd_freelist != nullptr) { |
| grpc_fd* fd = fd_freelist; |
| fd_freelist = fd_freelist->freelist_next; |
| gpr_mu_destroy(&fd->po.mu); |
| gpr_free(fd); |
| } |
| gpr_mu_destroy(&fd_freelist_mu); |
| } |
| |
| static grpc_fd* fd_create(int fd, const char* name) { |
| grpc_fd* new_fd = nullptr; |
| |
| gpr_mu_lock(&fd_freelist_mu); |
| if (fd_freelist != nullptr) { |
| new_fd = fd_freelist; |
| fd_freelist = fd_freelist->freelist_next; |
| } |
| gpr_mu_unlock(&fd_freelist_mu); |
| |
| if (new_fd == nullptr) { |
| new_fd = (grpc_fd*)gpr_malloc(sizeof(grpc_fd)); |
| gpr_mu_init(&new_fd->po.mu); |
| new_fd->read_closure.Init(); |
| new_fd->write_closure.Init(); |
| } |
| |
| /* Note: It is not really needed to get the new_fd->po.mu lock here. If this |
| * is a newly created fd (or an fd we got from the freelist), no one else |
| * would be holding a lock to it anyway. */ |
| gpr_mu_lock(&new_fd->po.mu); |
| new_fd->po.pi = nullptr; |
| #ifndef NDEBUG |
| new_fd->po.obj_type = POLL_OBJ_FD; |
| #endif |
| |
| gpr_atm_rel_store(&new_fd->refst, (gpr_atm)1); |
| new_fd->fd = fd; |
| new_fd->orphaned = false; |
| new_fd->read_closure->InitEvent(); |
| new_fd->write_closure->InitEvent(); |
| gpr_atm_no_barrier_store(&new_fd->read_notifier_pollset, (gpr_atm)NULL); |
| |
| new_fd->freelist_next = nullptr; |
| new_fd->on_done_closure = nullptr; |
| |
| gpr_mu_unlock(&new_fd->po.mu); |
| |
| char* fd_name; |
| gpr_asprintf(&fd_name, "%s fd=%d", name, fd); |
| grpc_iomgr_register_object(&new_fd->iomgr_object, fd_name); |
| gpr_free(fd_name); |
| return new_fd; |
| } |
| |
| static int fd_wrapped_fd(grpc_fd* fd) { |
| int ret_fd = -1; |
| gpr_mu_lock(&fd->po.mu); |
| if (!fd->orphaned) { |
| ret_fd = fd->fd; |
| } |
| gpr_mu_unlock(&fd->po.mu); |
| |
| return ret_fd; |
| } |
| |
| static void fd_orphan(grpc_fd* fd, grpc_closure* on_done, int* release_fd, |
| bool already_closed, const char* reason) { |
| grpc_error* error = GRPC_ERROR_NONE; |
| polling_island* unref_pi = nullptr; |
| |
| gpr_mu_lock(&fd->po.mu); |
| fd->on_done_closure = on_done; |
| |
| /* Remove the active status but keep referenced. We want this grpc_fd struct |
| to be alive (and not added to freelist) until the end of this function */ |
| REF_BY(fd, 1, reason); |
| |
| /* Remove the fd from the polling island: |
| - Get a lock on the latest polling island (i.e the last island in the |
| linked list pointed by fd->po.pi). This is the island that |
| would actually contain the fd |
| - Remove the fd from the latest polling island |
| - Unlock the latest polling island |
| - Set fd->po.pi to NULL (but remove the ref on the polling island |
| before doing this.) */ |
| if (fd->po.pi != nullptr) { |
| polling_island* pi_latest = polling_island_lock(fd->po.pi); |
| polling_island_remove_fd_locked(pi_latest, fd, already_closed, &error); |
| gpr_mu_unlock(&pi_latest->mu); |
| |
| unref_pi = fd->po.pi; |
| fd->po.pi = nullptr; |
| } |
| |
| /* If release_fd is not NULL, we should be relinquishing control of the file |
| descriptor fd->fd (but we still own the grpc_fd structure). */ |
| if (release_fd != nullptr) { |
| *release_fd = fd->fd; |
| } else { |
| close(fd->fd); |
| } |
| |
| fd->orphaned = true; |
| |
| GRPC_CLOSURE_SCHED(fd->on_done_closure, GRPC_ERROR_REF(error)); |
| |
| gpr_mu_unlock(&fd->po.mu); |
| UNREF_BY(fd, 2, reason); /* Drop the reference */ |
| if (unref_pi != nullptr) { |
| /* Unref stale polling island here, outside the fd lock above. |
| The polling island owns a workqueue which owns an fd, and unreffing |
| inside the lock can cause an eventual lock loop that makes TSAN very |
| unhappy. */ |
| PI_UNREF(unref_pi, "fd_orphan"); |
| } |
| if (error != GRPC_ERROR_NONE) { |
| const char* msg = grpc_error_string(error); |
| gpr_log(GPR_DEBUG, "fd_orphan: %s", msg); |
| } |
| GRPC_ERROR_UNREF(error); |
| } |
| |
| static grpc_pollset* fd_get_read_notifier_pollset(grpc_fd* fd) { |
| gpr_atm notifier = gpr_atm_acq_load(&fd->read_notifier_pollset); |
| return (grpc_pollset*)notifier; |
| } |
| |
| static bool fd_is_shutdown(grpc_fd* fd) { |
| return fd->read_closure->IsShutdown(); |
| } |
| |
| /* Might be called multiple times */ |
| static void fd_shutdown(grpc_fd* fd, grpc_error* why) { |
| if (fd->read_closure->SetShutdown(GRPC_ERROR_REF(why))) { |
| shutdown(fd->fd, SHUT_RDWR); |
| fd->write_closure->SetShutdown(GRPC_ERROR_REF(why)); |
| } |
| GRPC_ERROR_UNREF(why); |
| } |
| |
| static void fd_notify_on_read(grpc_fd* fd, grpc_closure* closure) { |
| fd->read_closure->NotifyOn(closure); |
| } |
| |
| static void fd_notify_on_write(grpc_fd* fd, grpc_closure* closure) { |
| fd->write_closure->NotifyOn(closure); |
| } |
| |
| /******************************************************************************* |
| * Pollset Definitions |
| */ |
| GPR_TLS_DECL(g_current_thread_pollset); |
| GPR_TLS_DECL(g_current_thread_worker); |
| static __thread bool g_initialized_sigmask; |
| static __thread sigset_t g_orig_sigmask; |
| |
| static void sig_handler(int sig_num) { |
| #ifdef GRPC_EPOLL_DEBUG |
| gpr_log(GPR_INFO, "Received signal %d", sig_num); |
| #endif |
| } |
| |
| static void poller_kick_init() { signal(grpc_wakeup_signal, sig_handler); } |
| |
| /* Global state management */ |
| static grpc_error* pollset_global_init(void) { |
| gpr_tls_init(&g_current_thread_pollset); |
| gpr_tls_init(&g_current_thread_worker); |
| poller_kick_init(); |
| return GRPC_ERROR_NONE; |
| } |
| |
| static void pollset_global_shutdown(void) { |
| gpr_tls_destroy(&g_current_thread_pollset); |
| gpr_tls_destroy(&g_current_thread_worker); |
| } |
| |
| static grpc_error* pollset_worker_kick(grpc_pollset_worker* worker) { |
| grpc_error* err = GRPC_ERROR_NONE; |
| |
| /* Kick the worker only if it was not already kicked */ |
| if (gpr_atm_no_barrier_cas(&worker->is_kicked, (gpr_atm)0, (gpr_atm)1)) { |
| GRPC_POLLING_TRACE( |
| "pollset_worker_kick: Kicking worker: %p (thread id: %ld)", |
| (void*)worker, (long int)worker->pt_id); |
| int err_num = pthread_kill(worker->pt_id, grpc_wakeup_signal); |
| if (err_num != 0) { |
| err = GRPC_OS_ERROR(err_num, "pthread_kill"); |
| } |
| } |
| return err; |
| } |
| |
| /* Return 1 if the pollset has active threads in pollset_work (pollset must |
| * be locked) */ |
| static int pollset_has_workers(grpc_pollset* p) { |
| return p->root_worker.next != &p->root_worker; |
| } |
| |
| static void remove_worker(grpc_pollset* p, grpc_pollset_worker* worker) { |
| worker->prev->next = worker->next; |
| worker->next->prev = worker->prev; |
| } |
| |
| static grpc_pollset_worker* pop_front_worker(grpc_pollset* p) { |
| if (pollset_has_workers(p)) { |
| grpc_pollset_worker* w = p->root_worker.next; |
| remove_worker(p, w); |
| return w; |
| } else { |
| return nullptr; |
| } |
| } |
| |
| static void push_back_worker(grpc_pollset* p, grpc_pollset_worker* worker) { |
| worker->next = &p->root_worker; |
| worker->prev = worker->next->prev; |
| worker->prev->next = worker->next->prev = worker; |
| } |
| |
| static void push_front_worker(grpc_pollset* p, grpc_pollset_worker* worker) { |
| worker->prev = &p->root_worker; |
| worker->next = worker->prev->next; |
| worker->prev->next = worker->next->prev = worker; |
| } |
| |
| /* p->mu must be held before calling this function */ |
| static grpc_error* pollset_kick(grpc_pollset* p, |
| grpc_pollset_worker* specific_worker) { |
| GPR_TIMER_BEGIN("pollset_kick", 0); |
| grpc_error* error = GRPC_ERROR_NONE; |
| GRPC_STATS_INC_POLLSET_KICK(); |
| const char* err_desc = "Kick Failure"; |
| grpc_pollset_worker* worker = specific_worker; |
| if (worker != nullptr) { |
| if (worker == GRPC_POLLSET_KICK_BROADCAST) { |
| if (pollset_has_workers(p)) { |
| GPR_TIMER_BEGIN("pollset_kick.broadcast", 0); |
| for (worker = p->root_worker.next; worker != &p->root_worker; |
| worker = worker->next) { |
| if (gpr_tls_get(&g_current_thread_worker) != (intptr_t)worker) { |
| append_error(&error, pollset_worker_kick(worker), err_desc); |
| } |
| } |
| GPR_TIMER_END("pollset_kick.broadcast", 0); |
| } else { |
| p->kicked_without_pollers = true; |
| } |
| } else { |
| GPR_TIMER_MARK("kicked_specifically", 0); |
| if (gpr_tls_get(&g_current_thread_worker) != (intptr_t)worker) { |
| append_error(&error, pollset_worker_kick(worker), err_desc); |
| } |
| } |
| } else if (gpr_tls_get(&g_current_thread_pollset) != (intptr_t)p) { |
| /* Since worker == NULL, it means that we can kick "any" worker on this |
| pollset 'p'. If 'p' happens to be the same pollset this thread is |
| currently polling (i.e in pollset_work() function), then there is no need |
| to kick any other worker since the current thread can just absorb the |
| kick. This is the reason why we enter this case only when |
| g_current_thread_pollset is != p */ |
| |
| GPR_TIMER_MARK("kick_anonymous", 0); |
| worker = pop_front_worker(p); |
| if (worker != nullptr) { |
| GPR_TIMER_MARK("finally_kick", 0); |
| push_back_worker(p, worker); |
| append_error(&error, pollset_worker_kick(worker), err_desc); |
| } else { |
| GPR_TIMER_MARK("kicked_no_pollers", 0); |
| p->kicked_without_pollers = true; |
| } |
| } |
| |
| GPR_TIMER_END("pollset_kick", 0); |
| GRPC_LOG_IF_ERROR("pollset_kick", GRPC_ERROR_REF(error)); |
| return error; |
| } |
| |
| static void pollset_init(grpc_pollset* pollset, gpr_mu** mu) { |
| gpr_mu_init(&pollset->po.mu); |
| *mu = &pollset->po.mu; |
| pollset->po.pi = nullptr; |
| #ifndef NDEBUG |
| pollset->po.obj_type = POLL_OBJ_POLLSET; |
| #endif |
| |
| pollset->root_worker.next = pollset->root_worker.prev = &pollset->root_worker; |
| pollset->kicked_without_pollers = false; |
| |
| pollset->shutting_down = false; |
| pollset->finish_shutdown_called = false; |
| pollset->shutdown_done = nullptr; |
| } |
| |
| static int poll_deadline_to_millis_timeout(grpc_millis millis) { |
| if (millis == GRPC_MILLIS_INF_FUTURE) return -1; |
| grpc_millis delta = millis - grpc_core::ExecCtx::Get()->Now(); |
| if (delta > INT_MAX) |
| return INT_MAX; |
| else if (delta < 0) |
| return 0; |
| else |
| return (int)delta; |
| } |
| |
| static void fd_become_readable(grpc_fd* fd, grpc_pollset* notifier) { |
| fd->read_closure->SetReady(); |
| |
| /* Note, it is possible that fd_become_readable might be called twice with |
| different 'notifier's when an fd becomes readable and it is in two epoll |
| sets (This can happen briefly during polling island merges). In such cases |
| it does not really matter which notifer is set as the read_notifier_pollset |
| (They would both point to the same polling island anyway) */ |
| /* Use release store to match with acquire load in fd_get_read_notifier */ |
| gpr_atm_rel_store(&fd->read_notifier_pollset, (gpr_atm)notifier); |
| } |
| |
| static void fd_become_writable(grpc_fd* fd) { fd->write_closure->SetReady(); } |
| |
| static void pollset_release_polling_island(grpc_pollset* ps, |
| const char* reason) { |
| if (ps->po.pi != nullptr) { |
| PI_UNREF(ps->po.pi, reason); |
| } |
| ps->po.pi = nullptr; |
| } |
| |
| static void finish_shutdown_locked(grpc_pollset* pollset) { |
| /* The pollset cannot have any workers if we are at this stage */ |
| GPR_ASSERT(!pollset_has_workers(pollset)); |
| |
| pollset->finish_shutdown_called = true; |
| |
| /* Release the ref and set pollset->po.pi to NULL */ |
| pollset_release_polling_island(pollset, "ps_shutdown"); |
| GRPC_CLOSURE_SCHED(pollset->shutdown_done, GRPC_ERROR_NONE); |
| } |
| |
| /* pollset->po.mu lock must be held by the caller before calling this */ |
| static void pollset_shutdown(grpc_pollset* pollset, grpc_closure* closure) { |
| GPR_TIMER_BEGIN("pollset_shutdown", 0); |
| GPR_ASSERT(!pollset->shutting_down); |
| pollset->shutting_down = true; |
| pollset->shutdown_done = closure; |
| pollset_kick(pollset, GRPC_POLLSET_KICK_BROADCAST); |
| |
| /* If the pollset has any workers, we cannot call finish_shutdown_locked() |
| because it would release the underlying polling island. In such a case, we |
| let the last worker call finish_shutdown_locked() from pollset_work() */ |
| if (!pollset_has_workers(pollset)) { |
| GPR_ASSERT(!pollset->finish_shutdown_called); |
| GPR_TIMER_MARK("pollset_shutdown.finish_shutdown_locked", 0); |
| finish_shutdown_locked(pollset); |
| } |
| GPR_TIMER_END("pollset_shutdown", 0); |
| } |
| |
| /* pollset_shutdown is guaranteed to be called before pollset_destroy. So other |
| * than destroying the mutexes, there is nothing special that needs to be done |
| * here */ |
| static void pollset_destroy(grpc_pollset* pollset) { |
| GPR_ASSERT(!pollset_has_workers(pollset)); |
| gpr_mu_destroy(&pollset->po.mu); |
| } |
| |
| #define GRPC_EPOLL_MAX_EVENTS 100 |
| /* Note: sig_mask contains the signal mask to use *during* epoll_wait() */ |
| static void pollset_work_and_unlock(grpc_pollset* pollset, |
| grpc_pollset_worker* worker, int timeout_ms, |
| sigset_t* sig_mask, grpc_error** error) { |
| struct epoll_event ep_ev[GRPC_EPOLL_MAX_EVENTS]; |
| int epoll_fd = -1; |
| int ep_rv; |
| polling_island* pi = nullptr; |
| char* err_msg; |
| const char* err_desc = "pollset_work_and_unlock"; |
| GPR_TIMER_BEGIN("pollset_work_and_unlock", 0); |
| |
| /* We need to get the epoll_fd to wait on. The epoll_fd is in inside the |
| latest polling island pointed by pollset->po.pi |
| |
| Since epoll_fd is immutable, we can read it without obtaining the polling |
| island lock. There is however a possibility that the polling island (from |
| which we got the epoll_fd) got merged with another island while we are |
| in this function. This is still okay because in such a case, we will wakeup |
| right-away from epoll_wait() and pick up the latest polling_island the next |
| this function (i.e pollset_work_and_unlock()) is called */ |
| |
| if (pollset->po.pi == nullptr) { |
| pollset->po.pi = polling_island_create(nullptr, error); |
| if (pollset->po.pi == nullptr) { |
| GPR_TIMER_END("pollset_work_and_unlock", 0); |
| return; /* Fatal error. We cannot continue */ |
| } |
| |
| PI_ADD_REF(pollset->po.pi, "ps"); |
| GRPC_POLLING_TRACE("pollset_work: pollset: %p created new pi: %p", |
| (void*)pollset, (void*)pollset->po.pi); |
| } |
| |
| pi = polling_island_maybe_get_latest(pollset->po.pi); |
| epoll_fd = pi->epoll_fd; |
| |
| /* Update the pollset->po.pi since the island being pointed by |
| pollset->po.pi maybe older than the one pointed by pi) */ |
| if (pollset->po.pi != pi) { |
| /* Always do PI_ADD_REF before PI_UNREF because PI_UNREF may cause the |
| polling island to be deleted */ |
| PI_ADD_REF(pi, "ps"); |
| PI_UNREF(pollset->po.pi, "ps"); |
| pollset->po.pi = pi; |
| } |
| |
| /* Add an extra ref so that the island does not get destroyed (which means |
| the epoll_fd won't be closed) while we are are doing an epoll_wait() on the |
| epoll_fd */ |
| PI_ADD_REF(pi, "ps_work"); |
| gpr_mu_unlock(&pollset->po.mu); |
| |
| gpr_atm_no_barrier_fetch_add(&pi->poller_count, 1); |
| g_current_thread_polling_island = pi; |
| |
| GRPC_SCHEDULING_START_BLOCKING_REGION; |
| GRPC_STATS_INC_SYSCALL_POLL(); |
| ep_rv = |
| epoll_pwait(epoll_fd, ep_ev, GRPC_EPOLL_MAX_EVENTS, timeout_ms, sig_mask); |
| GRPC_SCHEDULING_END_BLOCKING_REGION; |
| if (ep_rv < 0) { |
| if (errno != EINTR) { |
| gpr_asprintf(&err_msg, |
| "epoll_wait() epoll fd: %d failed with error: %d (%s)", |
| epoll_fd, errno, strerror(errno)); |
| append_error(error, GRPC_OS_ERROR(errno, err_msg), err_desc); |
| } else { |
| /* We were interrupted. Save an interation by doing a zero timeout |
| epoll_wait to see if there are any other events of interest */ |
| GRPC_POLLING_TRACE("pollset_work: pollset: %p, worker: %p received kick", |
| (void*)pollset, (void*)worker); |
| ep_rv = epoll_wait(epoll_fd, ep_ev, GRPC_EPOLL_MAX_EVENTS, 0); |
| } |
| } |
| |
| #ifdef GRPC_TSAN |
| /* See the definition of g_poll_sync for more details */ |
| gpr_atm_acq_load(&g_epoll_sync); |
| #endif /* defined(GRPC_TSAN) */ |
| |
| for (int i = 0; i < ep_rv; ++i) { |
| void* data_ptr = ep_ev[i].data.ptr; |
| if (data_ptr == &polling_island_wakeup_fd) { |
| GRPC_POLLING_TRACE( |
| "pollset_work: pollset: %p, worker: %p polling island (epoll_fd: " |
| "%d) got merged", |
| (void*)pollset, (void*)worker, epoll_fd); |
| /* This means that our polling island is merged with a different |
| island. We do not have to do anything here since the subsequent call |
| to the function pollset_work_and_unlock() will pick up the correct |
| epoll_fd */ |
| } else { |
| grpc_fd* fd = (grpc_fd*)data_ptr; |
| int cancel = ep_ev[i].events & (EPOLLERR | EPOLLHUP); |
| int read_ev = ep_ev[i].events & (EPOLLIN | EPOLLPRI); |
| int write_ev = ep_ev[i].events & EPOLLOUT; |
| if (read_ev || cancel) { |
| fd_become_readable(fd, pollset); |
| } |
| if (write_ev || cancel) { |
| fd_become_writable(fd); |
| } |
| } |
| } |
| |
| g_current_thread_polling_island = nullptr; |
| gpr_atm_no_barrier_fetch_add(&pi->poller_count, -1); |
| |
| GPR_ASSERT(pi != nullptr); |
| |
| /* Before leaving, release the extra ref we added to the polling island. It |
| is important to use "pi" here (i.e our old copy of pollset->po.pi |
| that we got before releasing the polling island lock). This is because |
| pollset->po.pi pointer might get udpated in other parts of the |
| code when there is an island merge while we are doing epoll_wait() above */ |
| PI_UNREF(pi, "ps_work"); |
| |
| GPR_TIMER_END("pollset_work_and_unlock", 0); |
| } |
| |
| /* pollset->po.mu lock must be held by the caller before calling this. |
| The function pollset_work() may temporarily release the lock (pollset->po.mu) |
| during the course of its execution but it will always re-acquire the lock and |
| ensure that it is held by the time the function returns */ |
| static grpc_error* pollset_work(grpc_pollset* pollset, |
| grpc_pollset_worker** worker_hdl, |
| grpc_millis deadline) { |
| GPR_TIMER_BEGIN("pollset_work", 0); |
| grpc_error* error = GRPC_ERROR_NONE; |
| int timeout_ms = poll_deadline_to_millis_timeout(deadline); |
| |
| sigset_t new_mask; |
| |
| grpc_pollset_worker worker; |
| worker.next = worker.prev = nullptr; |
| worker.pt_id = pthread_self(); |
| gpr_atm_no_barrier_store(&worker.is_kicked, (gpr_atm)0); |
| |
| if (worker_hdl) *worker_hdl = &worker; |
| |
| gpr_tls_set(&g_current_thread_pollset, (intptr_t)pollset); |
| gpr_tls_set(&g_current_thread_worker, (intptr_t)&worker); |
| |
| if (pollset->kicked_without_pollers) { |
| /* If the pollset was kicked without pollers, pretend that the current |
| worker got the kick and skip polling. A kick indicates that there is some |
| work that needs attention like an event on the completion queue or an |
| alarm */ |
| GPR_TIMER_MARK("pollset_work.kicked_without_pollers", 0); |
| pollset->kicked_without_pollers = 0; |
| } else if (!pollset->shutting_down) { |
| /* We use the posix-signal with number 'grpc_wakeup_signal' for waking up |
| (i.e 'kicking') a worker in the pollset. A 'kick' is a way to inform the |
| worker that there is some pending work that needs immediate attention |
| (like an event on the completion queue, or a polling island merge that |
| results in a new epoll-fd to wait on) and that the worker should not |
| spend time waiting in epoll_pwait(). |
| |
| A worker can be kicked anytime from the point it is added to the pollset |
| via push_front_worker() (or push_back_worker()) to the point it is |
| removed via remove_worker(). |
| If the worker is kicked before/during it calls epoll_pwait(), it should |
| immediately exit from epoll_wait(). If the worker is kicked after it |
| returns from epoll_wait(), then nothing really needs to be done. |
| |
| To accomplish this, we mask 'grpc_wakeup_signal' on this thread at all |
| times *except* when it is in epoll_pwait(). This way, the worker never |
| misses acting on a kick */ |
| |
| if (!g_initialized_sigmask) { |
| sigemptyset(&new_mask); |
| sigaddset(&new_mask, grpc_wakeup_signal); |
| pthread_sigmask(SIG_BLOCK, &new_mask, &g_orig_sigmask); |
| sigdelset(&g_orig_sigmask, grpc_wakeup_signal); |
| g_initialized_sigmask = true; |
| /* new_mask: The new thread mask which blocks 'grpc_wakeup_signal'. |
| This is the mask used at all times *except during |
| epoll_wait()*" |
| g_orig_sigmask: The thread mask which allows 'grpc_wakeup_signal' and |
| this is the mask to use *during epoll_wait()* |
| |
| The new_mask is set on the worker before it is added to the pollset |
| (i.e before it can be kicked) */ |
| } |
| |
| push_front_worker(pollset, &worker); /* Add worker to pollset */ |
| |
| pollset_work_and_unlock(pollset, &worker, timeout_ms, &g_orig_sigmask, |
| &error); |
| grpc_core::ExecCtx::Get()->Flush(); |
| |
| gpr_mu_lock(&pollset->po.mu); |
| |
| /* Note: There is no need to reset worker.is_kicked to 0 since we are no |
| longer going to use this worker */ |
| remove_worker(pollset, &worker); |
| } |
| |
| /* If we are the last worker on the pollset (i.e pollset_has_workers() is |
| false at this point) and the pollset is shutting down, we may have to |
| finish the shutdown process by calling finish_shutdown_locked(). |
| See pollset_shutdown() for more details. |
| |
| Note: Continuing to access pollset here is safe; it is the caller's |
| responsibility to not destroy a pollset when it has outstanding calls to |
| pollset_work() */ |
| if (pollset->shutting_down && !pollset_has_workers(pollset) && |
| !pollset->finish_shutdown_called) { |
| GPR_TIMER_MARK("pollset_work.finish_shutdown_locked", 0); |
| finish_shutdown_locked(pollset); |
| |
| gpr_mu_unlock(&pollset->po.mu); |
| grpc_core::ExecCtx::Get()->Flush(); |
| gpr_mu_lock(&pollset->po.mu); |
| } |
| |
| if (worker_hdl) *worker_hdl = nullptr; |
| |
| gpr_tls_set(&g_current_thread_pollset, (intptr_t)0); |
| gpr_tls_set(&g_current_thread_worker, (intptr_t)0); |
| |
| GPR_TIMER_END("pollset_work", 0); |
| |
| GRPC_LOG_IF_ERROR("pollset_work", GRPC_ERROR_REF(error)); |
| return error; |
| } |
| |
| static void add_poll_object(poll_obj* bag, poll_obj_type bag_type, |
| poll_obj* item, poll_obj_type item_type) { |
| GPR_TIMER_BEGIN("add_poll_object", 0); |
| |
| #ifndef NDEBUG |
| GPR_ASSERT(item->obj_type == item_type); |
| GPR_ASSERT(bag->obj_type == bag_type); |
| #endif |
| |
| grpc_error* error = GRPC_ERROR_NONE; |
| polling_island* pi_new = nullptr; |
| |
| gpr_mu_lock(&bag->mu); |
| gpr_mu_lock(&item->mu); |
| |
| retry: |
| /* |
| * 1) If item->pi and bag->pi are both non-NULL and equal, do nothing |
| * 2) If item->pi and bag->pi are both NULL, create a new polling island (with |
| * a refcount of 2) and point item->pi and bag->pi to the new island |
| * 3) If exactly one of item->pi or bag->pi is NULL, update it to point to |
| * the other's non-NULL pi |
| * 4) Finally if item->pi and bag-pi are non-NULL and not-equal, merge the |
| * polling islands and update item->pi and bag->pi to point to the new |
| * island |
| */ |
| |
| /* Early out if we are trying to add an 'fd' to a 'bag' but the fd is already |
| * orphaned */ |
| if (item_type == POLL_OBJ_FD && (FD_FROM_PO(item))->orphaned) { |
| gpr_mu_unlock(&item->mu); |
| gpr_mu_unlock(&bag->mu); |
| return; |
| } |
| |
| if (item->pi == bag->pi) { |
| pi_new = item->pi; |
| if (pi_new == nullptr) { |
| /* GPR_ASSERT(item->pi == bag->pi == NULL) */ |
| |
| /* If we are adding an fd to a bag (i.e pollset or pollset_set), then |
| * we need to do some extra work to make TSAN happy */ |
| if (item_type == POLL_OBJ_FD) { |
| /* Unlock before creating a new polling island: the polling island will |
| create a workqueue which creates a file descriptor, and holding an fd |
| lock here can eventually cause a loop to appear to TSAN (making it |
| unhappy). We don't think it's a real loop (there's an epoch point |
| where that loop possibility disappears), but the advantages of |
| keeping TSAN happy outweigh any performance advantage we might have |
| by keeping the lock held. */ |
| gpr_mu_unlock(&item->mu); |
| pi_new = polling_island_create(FD_FROM_PO(item), &error); |
| gpr_mu_lock(&item->mu); |
| |
| /* Need to reverify any assumptions made between the initial lock and |
| getting to this branch: if they've changed, we need to throw away our |
| work and figure things out again. */ |
| if (item->pi != nullptr) { |
| GRPC_POLLING_TRACE( |
| "add_poll_object: Raced creating new polling island. pi_new: %p " |
| "(fd: %d, %s: %p)", |
| (void*)pi_new, FD_FROM_PO(item)->fd, poll_obj_string(bag_type), |
| (void*)bag); |
| /* No need to lock 'pi_new' here since this is a new polling island |
| and no one has a reference to it yet */ |
| polling_island_remove_all_fds_locked(pi_new, true, &error); |
| |
| /* Ref and unref so that the polling island gets deleted during unref |
| */ |
| PI_ADD_REF(pi_new, "dance_of_destruction"); |
| PI_UNREF(pi_new, "dance_of_destruction"); |
| goto retry; |
| } |
| } else { |
| pi_new = polling_island_create(nullptr, &error); |
| } |
| |
| GRPC_POLLING_TRACE( |
| "add_poll_object: Created new polling island. pi_new: %p (%s: %p, " |
| "%s: %p)", |
| (void*)pi_new, poll_obj_string(item_type), (void*)item, |
| poll_obj_string(bag_type), (void*)bag); |
| } else { |
| GRPC_POLLING_TRACE( |
| "add_poll_object: Same polling island. pi: %p (%s, %s)", |
| (void*)pi_new, poll_obj_string(item_type), poll_obj_string(bag_type)); |
| } |
| } else if (item->pi == nullptr) { |
| /* GPR_ASSERT(bag->pi != NULL) */ |
| /* Make pi_new point to latest pi*/ |
| pi_new = polling_island_lock(bag->pi); |
| |
| if (item_type == POLL_OBJ_FD) { |
| grpc_fd* fd = FD_FROM_PO(item); |
| polling_island_add_fds_locked(pi_new, &fd, 1, true, &error); |
| } |
| |
| gpr_mu_unlock(&pi_new->mu); |
| GRPC_POLLING_TRACE( |
| "add_poll_obj: item->pi was NULL. pi_new: %p (item(%s): %p, " |
| "bag(%s): %p)", |
| (void*)pi_new, poll_obj_string(item_type), (void*)item, |
| poll_obj_string(bag_type), (void*)bag); |
| } else if (bag->pi == nullptr) { |
| /* GPR_ASSERT(item->pi != NULL) */ |
| /* Make pi_new to point to latest pi */ |
| pi_new = polling_island_lock(item->pi); |
| gpr_mu_unlock(&pi_new->mu); |
| GRPC_POLLING_TRACE( |
| "add_poll_obj: bag->pi was NULL. pi_new: %p (item(%s): %p, " |
| "bag(%s): %p)", |
| (void*)pi_new, poll_obj_string(item_type), (void*)item, |
| poll_obj_string(bag_type), (void*)bag); |
| } else { |
| pi_new = polling_island_merge(item->pi, bag->pi, &error); |
| GRPC_POLLING_TRACE( |
| "add_poll_obj: polling islands merged. pi_new: %p (item(%s): %p, " |
| "bag(%s): %p)", |
| (void*)pi_new, poll_obj_string(item_type), (void*)item, |
| poll_obj_string(bag_type), (void*)bag); |
| } |
| |
| /* At this point, pi_new is the polling island that both item->pi and bag->pi |
| MUST be pointing to */ |
| |
| if (item->pi != pi_new) { |
| PI_ADD_REF(pi_new, poll_obj_string(item_type)); |
| if (item->pi != nullptr) { |
| PI_UNREF(item->pi, poll_obj_string(item_type)); |
| } |
| item->pi = pi_new; |
| } |
| |
| if (bag->pi != pi_new) { |
| PI_ADD_REF(pi_new, poll_obj_string(bag_type)); |
| if (bag->pi != nullptr) { |
| PI_UNREF(bag->pi, poll_obj_string(bag_type)); |
| } |
| bag->pi = pi_new; |
| } |
| |
| gpr_mu_unlock(&item->mu); |
| gpr_mu_unlock(&bag->mu); |
| |
| GRPC_LOG_IF_ERROR("add_poll_object", error); |
| GPR_TIMER_END("add_poll_object", 0); |
| } |
| |
| static void pollset_add_fd(grpc_pollset* pollset, grpc_fd* fd) { |
| add_poll_object(&pollset->po, POLL_OBJ_POLLSET, &fd->po, POLL_OBJ_FD); |
| } |
| |
| /******************************************************************************* |
| * Pollset-set Definitions |
| */ |
| |
| static grpc_pollset_set* pollset_set_create(void) { |
| grpc_pollset_set* pss = (grpc_pollset_set*)gpr_malloc(sizeof(*pss)); |
| gpr_mu_init(&pss->po.mu); |
| pss->po.pi = nullptr; |
| #ifndef NDEBUG |
| pss->po.obj_type = POLL_OBJ_POLLSET_SET; |
| #endif |
| return pss; |
| } |
| |
| static void pollset_set_destroy(grpc_pollset_set* pss) { |
| gpr_mu_destroy(&pss->po.mu); |
| |
| if (pss->po.pi != nullptr) { |
| PI_UNREF(pss->po.pi, "pss_destroy"); |
| } |
| |
| gpr_free(pss); |
| } |
| |
| static void pollset_set_add_fd(grpc_pollset_set* pss, grpc_fd* fd) { |
| add_poll_object(&pss->po, POLL_OBJ_POLLSET_SET, &fd->po, POLL_OBJ_FD); |
| } |
| |
| static void pollset_set_del_fd(grpc_pollset_set* pss, grpc_fd* fd) { |
| /* Nothing to do */ |
| } |
| |
| static void pollset_set_add_pollset(grpc_pollset_set* pss, grpc_pollset* ps) { |
| add_poll_object(&pss->po, POLL_OBJ_POLLSET_SET, &ps->po, POLL_OBJ_POLLSET); |
| } |
| |
| static void pollset_set_del_pollset(grpc_pollset_set* pss, grpc_pollset* ps) { |
| /* Nothing to do */ |
| } |
| |
| static void pollset_set_add_pollset_set(grpc_pollset_set* bag, |
| grpc_pollset_set* item) { |
| add_poll_object(&bag->po, POLL_OBJ_POLLSET_SET, &item->po, |
| POLL_OBJ_POLLSET_SET); |
| } |
| |
| static void pollset_set_del_pollset_set(grpc_pollset_set* bag, |
| grpc_pollset_set* item) { |
| /* Nothing to do */ |
| } |
| |
| /* Test helper functions |
| * */ |
| void* grpc_fd_get_polling_island(grpc_fd* fd) { |
| polling_island* pi; |
| |
| gpr_mu_lock(&fd->po.mu); |
| pi = fd->po.pi; |
| gpr_mu_unlock(&fd->po.mu); |
| |
| return pi; |
| } |
| |
| void* grpc_pollset_get_polling_island(grpc_pollset* ps) { |
| polling_island* pi; |
| |
| gpr_mu_lock(&ps->po.mu); |
| pi = ps->po.pi; |
| gpr_mu_unlock(&ps->po.mu); |
| |
| return pi; |
| } |
| |
| bool grpc_are_polling_islands_equal(void* p, void* q) { |
| polling_island* p1 = (polling_island*)p; |
| polling_island* p2 = (polling_island*)q; |
| |
| /* Note: polling_island_lock_pair() may change p1 and p2 to point to the |
| latest polling islands in their respective linked lists */ |
| polling_island_lock_pair(&p1, &p2); |
| polling_island_unlock_pair(p1, p2); |
| |
| return p1 == p2; |
| } |
| |
| /******************************************************************************* |
| * Event engine binding |
| */ |
| |
| static void shutdown_engine(void) { |
| fd_global_shutdown(); |
| pollset_global_shutdown(); |
| polling_island_global_shutdown(); |
| } |
| |
| static const grpc_event_engine_vtable vtable = { |
| sizeof(grpc_pollset), |
| |
| fd_create, |
| fd_wrapped_fd, |
| fd_orphan, |
| fd_shutdown, |
| fd_notify_on_read, |
| fd_notify_on_write, |
| fd_is_shutdown, |
| fd_get_read_notifier_pollset, |
| |
| pollset_init, |
| pollset_shutdown, |
| pollset_destroy, |
| pollset_work, |
| pollset_kick, |
| pollset_add_fd, |
| |
| pollset_set_create, |
| pollset_set_destroy, |
| pollset_set_add_pollset, |
| pollset_set_del_pollset, |
| pollset_set_add_pollset_set, |
| pollset_set_del_pollset_set, |
| pollset_set_add_fd, |
| pollset_set_del_fd, |
| |
| shutdown_engine, |
| }; |
| |
| /* It is possible that GLIBC has epoll but the underlying kernel doesn't. |
| * Create a dummy epoll_fd to make sure epoll support is available */ |
| static bool is_epoll_available() { |
| int fd = epoll_create1(EPOLL_CLOEXEC); |
| if (fd < 0) { |
| gpr_log( |
| GPR_ERROR, |
| "epoll_create1 failed with error: %d. Not using epoll polling engine", |
| fd); |
| return false; |
| } |
| close(fd); |
| return true; |
| } |
| |
| const grpc_event_engine_vtable* grpc_init_epollsig_linux( |
| bool explicit_request) { |
| /* If use of signals is disabled, we cannot use epoll engine*/ |
| if (is_grpc_wakeup_signal_initialized && grpc_wakeup_signal < 0) { |
| gpr_log(GPR_ERROR, "Skipping epollsig because use of signals is disabled."); |
| return nullptr; |
| } |
| |
| if (!grpc_has_wakeup_fd()) { |
| gpr_log(GPR_ERROR, "Skipping epollsig because of no wakeup fd."); |
| return nullptr; |
| } |
| |
| if (!is_epoll_available()) { |
| gpr_log(GPR_ERROR, "Skipping epollsig because epoll is unavailable."); |
| return nullptr; |
| } |
| |
| if (!is_grpc_wakeup_signal_initialized) { |
| if (explicit_request) { |
| grpc_use_signal(SIGRTMIN + 6); |
| } else { |
| gpr_log(GPR_ERROR, |
| "Skipping epollsig because uninitialized wakeup signal."); |
| return nullptr; |
| } |
| } |
| |
| fd_global_init(); |
| |
| if (!GRPC_LOG_IF_ERROR("pollset_global_init", pollset_global_init())) { |
| return nullptr; |
| } |
| |
| if (!GRPC_LOG_IF_ERROR("polling_island_global_init", |
| polling_island_global_init())) { |
| return nullptr; |
| } |
| |
| return &vtable; |
| } |
| |
| #else /* defined(GRPC_LINUX_EPOLL) */ |
| #if defined(GRPC_POSIX_SOCKET) |
| #include "src/core/lib/iomgr/ev_epollsig_linux.h" |
| /* If GRPC_LINUX_EPOLL is not defined, it means epoll is not available. Return |
| * NULL */ |
| const grpc_event_engine_vtable* grpc_init_epollsig_linux( |
| bool explicit_request) { |
| return nullptr; |
| } |
| #endif /* defined(GRPC_POSIX_SOCKET) */ |
| |
| void grpc_use_signal(int signum) {} |
| #endif /* !defined(GRPC_LINUX_EPOLL) */ |