Initial fork for singleton epoll poller
diff --git a/src/core/lib/iomgr/ev_epoll1_linux.c b/src/core/lib/iomgr/ev_epoll1_linux.c
new file mode 100644
index 0000000..3c7a16b
--- /dev/null
+++ b/src/core/lib/iomgr/ev_epoll1_linux.c
@@ -0,0 +1,579 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ * * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/lib/iomgr/port.h"
+
+/* This polling engine is only relevant on linux kernels supporting epoll() */
+#ifdef GRPC_LINUX_EPOLL
+
+#include "src/core/lib/iomgr/ev_epoll_linux.h"
+
+#include <assert.h>
+#include <errno.h>
+#include <poll.h>
+#include <pthread.h>
+#include <string.h>
+#include <sys/epoll.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/tls.h>
+#include <grpc/support/useful.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/iomgr/workqueue.h"
+#include "src/core/lib/profiling/timers.h"
+#include "src/core/lib/support/block_annotate.h"
+
+/* TODO: sreek: Right now, this wakes up all pollers. In future we should make
+ * sure to wake up one polling thread (which can wake up other threads if
+ * needed) */
+static grpc_wakeup_fd global_wakeup_fd;
+static int g_epfd;
+
+/*******************************************************************************
+ * Fd Declarations
+ */
+
+struct grpc_fd {
+ int fd;
+
+ /* 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;
+
+ gpr_atm read_closure;
+ gpr_atm 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;
+};
+
+static void fd_global_init(void);
+static void fd_global_shutdown(void);
+
+/*******************************************************************************
+ * Pollset Declarations
+ */
+
+typedef struct pollset_worker_link {
+ grpc_pollset_worker *next;
+ grpc_pollset_worker *prev;
+} pollset_worker_link;
+
+typedef enum {
+ PWL_POLLSET,
+ PWL_POLLABLE,
+ POLLSET_WORKER_LINK_COUNT
+} pollset_worker_links;
+
+struct grpc_pollset_worker {
+ bool kicked;
+ bool initialized_cv;
+ pollset_worker_link links[POLLSET_WORKER_LINK_COUNT];
+ gpr_cv cv;
+};
+
+struct grpc_pollset {
+ 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 {};
+
+/*******************************************************************************
+ * 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;
+}
+
+/*******************************************************************************
+ * 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 = NULL;
+static gpr_mu fd_freelist_mu;
+
+#ifdef GRPC_FD_REF_COUNT_DEBUG
+#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) {
+ gpr_log(GPR_DEBUG, "FD %d %p ref %d %ld -> %ld [%s; %s:%d]", fd->fd,
+ (void *)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);
+}
+
+#ifdef GRPC_FD_REF_COUNT_DEBUG
+static void unref_by(grpc_fd *fd, int n, const char *reason, const char *file,
+ int line) {
+ gpr_atm old;
+ gpr_log(GPR_DEBUG, "FD %d %p unref %d %ld -> %ld [%s; %s:%d]", fd->fd,
+ (void *)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) {
+ gpr_atm old;
+#endif
+ 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);
+
+ grpc_lfev_destroy(&fd->read_closure);
+ grpc_lfev_destroy(&fd->write_closure);
+
+ gpr_mu_unlock(&fd_freelist_mu);
+ } else {
+ GPR_ASSERT(old > n);
+ }
+}
+
+/* Increment refcount by two to avoid changing the orphan bit */
+#ifdef GRPC_FD_REF_COUNT_DEBUG
+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 != NULL) {
+ 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 = NULL;
+
+ gpr_mu_lock(&fd_freelist_mu);
+ if (fd_freelist != NULL) {
+ new_fd = fd_freelist;
+ fd_freelist = fd_freelist->freelist_next;
+ }
+ gpr_mu_unlock(&fd_freelist_mu);
+
+ if (new_fd == NULL) {
+ new_fd = gpr_malloc(sizeof(grpc_fd));
+ gpr_mu_init(&new_fd->po.mu);
+ }
+
+ /* 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 = NULL;
+#ifdef PO_DEBUG
+ 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;
+ grpc_lfev_init(&new_fd->read_closure);
+ grpc_lfev_init(&new_fd->write_closure);
+ gpr_atm_no_barrier_store(&new_fd->read_notifier_pollset, (gpr_atm)NULL);
+
+ new_fd->freelist_next = NULL;
+ new_fd->on_done_closure = NULL;
+
+ 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);
+#ifdef GRPC_FD_REF_COUNT_DEBUG
+ gpr_log(GPR_DEBUG, "FD %d %p create %s", fd, (void *)new_fd, fd_name);
+#endif
+ 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_exec_ctx *exec_ctx, grpc_fd *fd,
+ grpc_closure *on_done, int *release_fd,
+ const char *reason) {
+ bool is_fd_closed = false;
+ grpc_error *error = GRPC_ERROR_NONE;
+ polling_island *unref_pi = NULL;
+
+ gpr_mu_lock(&fd->po.mu);
+ fd->on_done_closure = on_done;
+
+ /* 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 != NULL) {
+ *release_fd = fd->fd;
+ } else {
+ close(fd->fd);
+ is_fd_closed = true;
+ }
+
+ fd->orphaned = true;
+
+ /* 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 != NULL) {
+ polling_island *pi_latest = polling_island_lock(fd->po.pi);
+ polling_island_remove_fd_locked(pi_latest, fd, is_fd_closed, &error);
+ gpr_mu_unlock(&pi_latest->mu);
+
+ unref_pi = fd->po.pi;
+ fd->po.pi = NULL;
+ }
+
+ grpc_closure_sched(exec_ctx, 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 != NULL) {
+ /* 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(exec_ctx, unref_pi, "fd_orphan");
+ }
+ GRPC_LOG_IF_ERROR("fd_orphan", GRPC_ERROR_REF(error));
+ GRPC_ERROR_UNREF(error);
+}
+
+static grpc_pollset *fd_get_read_notifier_pollset(grpc_exec_ctx *exec_ctx,
+ 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 grpc_lfev_is_shutdown(&fd->read_closure);
+}
+
+/* Might be called multiple times */
+static void fd_shutdown(grpc_exec_ctx *exec_ctx, grpc_fd *fd, grpc_error *why) {
+ if (grpc_lfev_set_shutdown(exec_ctx, &fd->read_closure,
+ GRPC_ERROR_REF(why))) {
+ shutdown(fd->fd, SHUT_RDWR);
+ grpc_lfev_set_shutdown(exec_ctx, &fd->write_closure, GRPC_ERROR_REF(why));
+ }
+ GRPC_ERROR_UNREF(why);
+}
+
+static void fd_notify_on_read(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
+ grpc_closure *closure) {
+ grpc_lfev_notify_on(exec_ctx, &fd->read_closure, closure);
+}
+
+static void fd_notify_on_write(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
+ grpc_closure *closure) {
+ grpc_lfev_notify_on(exec_ctx, &fd->write_closure, closure);
+}
+
+static grpc_workqueue *fd_get_workqueue(grpc_fd *fd) {
+ gpr_mu_lock(&fd->po.mu);
+ grpc_workqueue *workqueue =
+ GRPC_WORKQUEUE_REF((grpc_workqueue *)fd->po.pi, "fd_get_workqueue");
+ gpr_mu_unlock(&fd->po.mu);
+ return workqueue;
+}
+
+/*******************************************************************************
+ * Pollset Definitions
+ */
+
+/* Return true if first in list */
+static bool worker_insert(grpc_pollset_worker **root, pollset_worker_links link,
+ grpc_pollset_worker *worker) {
+ if (*root == NULL) {
+ *root = worker;
+ worker->links[link].next = worker->links[link].prev = worker;
+ return true;
+ } else {
+ worker->links[link].next = *root;
+ worker->links[link].prev = worker->links[link].next->links[link].prev;
+ worker->links[link].next->links[link].prev = worker;
+ worker->links[link].prev->links[link].next = worker;
+ return false;
+ }
+}
+
+/* Return true if last in list */
+typedef enum { EMPTIED, NEW_ROOT, REMOVED } worker_remove_result;
+
+static worker_remove_result worker_remove(grpc_pollset_worker **root,
+ pollset_worker_links link,
+ grpc_pollset_worker *worker) {
+ if (worker == *root) {
+ if (worker == worker->links[link].next) {
+ *root = NULL;
+ return EMPTIED;
+ } else {
+ *root = worker->links[link].next;
+ worker->links[link].prev->links[link].next = worker->links[link].next;
+ worker->links[link].next->links[link].prev = worker->links[link].prev;
+ return NEW_ROOT;
+ }
+ } else {
+ worker->links[link].prev->links[link].next = worker->links[link].next;
+ worker->links[link].next->links[link].prev = worker->links[link].prev;
+ return REMOVED;
+ }
+}
+
+GPR_TLS_DECL(g_current_thread_pollset);
+GPR_TLS_DECL(g_current_thread_worker);
+
+/*******************************************************************************
+ * Pollset-set Definitions
+ */
+
+static grpc_pollset_set *pollset_set_create(void) {
+ return (grpc_pollset_set *)((intptr_t)0xdeafbeef);
+}
+
+static void pollset_set_destroy(grpc_exec_ctx *exec_ctx,
+ grpc_pollset_set *pss) {}
+
+static void pollset_set_add_fd(grpc_exec_ctx *exec_ctx, grpc_pollset_set *pss,
+ grpc_fd *fd) {}
+
+static void pollset_set_del_fd(grpc_exec_ctx *exec_ctx, grpc_pollset_set *pss,
+ grpc_fd *fd) {}
+
+static void pollset_set_add_pollset(grpc_exec_ctx *exec_ctx,
+ grpc_pollset_set *pss, grpc_pollset *ps) {}
+
+static void pollset_set_del_pollset(grpc_exec_ctx *exec_ctx,
+ grpc_pollset_set *pss, grpc_pollset *ps) {}
+
+static void pollset_set_add_pollset_set(grpc_exec_ctx *exec_ctx,
+ grpc_pollset_set *bag,
+ grpc_pollset_set *item) {}
+
+static void pollset_set_del_pollset_set(grpc_exec_ctx *exec_ctx,
+ grpc_pollset_set *bag,
+ grpc_pollset_set *item) {}
+
+/*******************************************************************************
+ * 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 = {
+ .pollset_size = sizeof(grpc_pollset),
+
+ .fd_create = fd_create,
+ .fd_wrapped_fd = fd_wrapped_fd,
+ .fd_orphan = fd_orphan,
+ .fd_shutdown = fd_shutdown,
+ .fd_is_shutdown = fd_is_shutdown,
+ .fd_notify_on_read = fd_notify_on_read,
+ .fd_notify_on_write = fd_notify_on_write,
+ .fd_get_read_notifier_pollset = fd_get_read_notifier_pollset,
+ .fd_get_workqueue = fd_get_workqueue,
+
+ .pollset_init = pollset_init,
+ .pollset_shutdown = pollset_shutdown,
+ .pollset_destroy = pollset_destroy,
+ .pollset_work = pollset_work,
+ .pollset_kick = pollset_kick,
+ .pollset_add_fd = pollset_add_fd,
+
+ .pollset_set_create = pollset_set_create,
+ .pollset_set_destroy = pollset_set_destroy,
+ .pollset_set_add_pollset = pollset_set_add_pollset,
+ .pollset_set_del_pollset = pollset_set_del_pollset,
+ .pollset_set_add_pollset_set = pollset_set_add_pollset_set,
+ .pollset_set_del_pollset_set = pollset_set_del_pollset_set,
+ .pollset_set_add_fd = pollset_set_add_fd,
+ .pollset_set_del_fd = pollset_set_del_fd,
+
+ .kick_poller = kick_poller,
+
+ .workqueue_ref = workqueue_ref,
+ .workqueue_unref = workqueue_unref,
+ .workqueue_scheduler = workqueue_scheduler,
+
+ .shutdown_engine = 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_epoll1_linux(void) {
+ /* If use of signals is disabled, we cannot use epoll engine*/
+ if (is_grpc_wakeup_signal_initialized && grpc_wakeup_signal < 0) {
+ return NULL;
+ }
+
+ if (!grpc_has_wakeup_fd()) {
+ return NULL;
+ }
+
+ if (!is_epoll_available()) {
+ return NULL;
+ }
+
+ if (!is_grpc_wakeup_signal_initialized) {
+ grpc_use_signal(SIGRTMIN + 6);
+ }
+
+ fd_global_init();
+
+ if (!GRPC_LOG_IF_ERROR("pollset_global_init", pollset_global_init())) {
+ return NULL;
+ }
+
+ if (!GRPC_LOG_IF_ERROR("polling_island_global_init",
+ polling_island_global_init())) {
+ return NULL;
+ }
+
+ return &vtable;
+}
+
+#else /* defined(GRPC_LINUX_EPOLL) */
+#if defined(GRPC_POSIX_SOCKET)
+#include "src/core/lib/iomgr/ev_posix.h"
+/* If GRPC_LINUX_EPOLL is not defined, it means epoll is not available. Return
+ * NULL */
+const grpc_event_engine_vtable *grpc_init_epoll1_linux(void) { return NULL; }
+#endif /* defined(GRPC_POSIX_SOCKET) */
+#endif /* !defined(GRPC_LINUX_EPOLL) */