| /* |
| * |
| * Copyright 2015, 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. |
| * |
| */ |
| |
| /* Available log space is divided up in blocks of |
| CENSUS_LOG_2_MAX_RECORD_SIZE bytes. A block can be in one of the |
| following three data structures: |
| - Free blocks (free_block_list) |
| - Blocks with unread data (dirty_block_list) |
| - Blocks currently attached to cores (core_local_blocks[]) |
| |
| census_log_start_write() moves a block from core_local_blocks[] to the |
| end of dirty_block_list when block: |
| - is out-of-space OR |
| - has an incomplete record (an incomplete record occurs when a thread calls |
| census_log_start_write() and is context-switched before calling |
| census_log_end_write() |
| So, blocks in dirty_block_list are ordered, from oldest to newest, by time |
| when block is detached from the core. |
| |
| census_log_read_next() first iterates over dirty_block_list and then |
| core_local_blocks[]. It moves completely read blocks from dirty_block_list |
| to free_block_list. Blocks in core_local_blocks[] are not freed, even when |
| completely read. |
| |
| If log is configured to discard old records and free_block_list is empty, |
| census_log_start_write() iterates over dirty_block_list to allocate a |
| new block. It moves the oldest available block (no pending read/write) to |
| core_local_blocks[]. |
| |
| core_local_block_struct is used to implement a map from core id to the block |
| associated with that core. This mapping is advisory. It is possible that the |
| block returned by this mapping is no longer associated with that core. This |
| mapping is updated, lazily, by census_log_start_write(). |
| |
| Locking in block struct: |
| |
| Exclusive g_log.lock must be held before calling any functions operatong on |
| block structs except census_log_start_write() and |
| census_log_end_write(). |
| |
| Writes to a block are serialized via writer_lock. |
| census_log_start_write() acquires this lock and |
| census_log_end_write() releases it. On failure to acquire the lock, |
| writer allocates a new block for the current core and updates |
| core_local_block accordingly. |
| |
| Simultaneous read and write access is allowed. Reader can safely read up to |
| committed bytes (bytes_committed). |
| |
| reader_lock protects the block, currently being read, from getting recycled. |
| start_read() acquires reader_lock and end_read() releases the lock. |
| |
| Read/write access to a block is disabled via try_disable_access(). It returns |
| with both writer_lock and reader_lock held. These locks are subsequently |
| released by enable_access() to enable access to the block. |
| |
| A note on naming: Most function/struct names are prepended by cl_ |
| (shorthand for census_log). Further, functions that manipulate structures |
| include the name of the structure, which will be passed as the first |
| argument. E.g. cl_block_initialize() will initialize a cl_block. |
| */ |
| #include "src/core/statistics/census_log.h" |
| #include <string.h> |
| #include <grpc/support/alloc.h> |
| #include <grpc/support/atm.h> |
| #include <grpc/support/cpu.h> |
| #include <grpc/support/log.h> |
| #include <grpc/support/port_platform.h> |
| #include <grpc/support/sync.h> |
| #include <grpc/support/useful.h> |
| |
| /* End of platform specific code */ |
| |
| typedef struct census_log_block_list_struct { |
| struct census_log_block_list_struct* next; |
| struct census_log_block_list_struct* prev; |
| struct census_log_block* block; |
| } cl_block_list_struct; |
| |
| typedef struct census_log_block { |
| /* Pointer to underlying buffer */ |
| char* buffer; |
| gpr_atm writer_lock; |
| gpr_atm reader_lock; |
| /* Keeps completely written bytes. Declared atomic because accessed |
| simultaneously by reader and writer. */ |
| gpr_atm bytes_committed; |
| /* Bytes already read */ |
| gpr_int32 bytes_read; |
| /* Links for list */ |
| cl_block_list_struct link; |
| /* We want this structure to be cacheline aligned. We assume the following |
| sizes for the various parts on 32/64bit systems: |
| type 32b size 64b size |
| char* 4 8 |
| 3x gpr_atm 12 24 |
| gpr_int32 4 8 (assumes padding) |
| cl_block_list_struct 12 24 |
| TOTAL 32 64 |
| |
| Depending on the size of our cacheline and the architecture, we |
| selectively add char buffering to this structure. The size is checked |
| via assert in census_log_initialize(). */ |
| #if defined(GPR_ARCH_64) |
| #define CL_BLOCK_PAD_SIZE (GPR_CACHELINE_SIZE - 64) |
| #else |
| #if defined(GPR_ARCH_32) |
| #define CL_BLOCK_PAD_SIZE (GPR_CACHELINE_SIZE - 32) |
| #else |
| #error "Unknown architecture" |
| #endif |
| #endif |
| #if CL_BLOCK_PAD_SIZE > 0 |
| char padding[CL_BLOCK_PAD_SIZE]; |
| #endif |
| } cl_block; |
| |
| /* A list of cl_blocks, doubly-linked through cl_block::link. */ |
| typedef struct census_log_block_list { |
| gpr_int32 count; /* Number of items in list. */ |
| cl_block_list_struct ht; /* head/tail of linked list. */ |
| } cl_block_list; |
| |
| /* Cacheline aligned block pointers to avoid false sharing. Block pointer must |
| be initialized via set_block(), before calling other functions */ |
| typedef struct census_log_core_local_block { |
| gpr_atm block; |
| /* Ensure cachline alignment: we assume sizeof(gpr_atm) == 4 or 8 */ |
| #if defined(GPR_ARCH_64) |
| #define CL_CORE_LOCAL_BLOCK_PAD_SIZE (GPR_CACHELINE_SIZE - 8) |
| #else |
| #if defined(GPR_ARCH_32) |
| #define CL_CORE_LOCAL_BLOCK_PAD_SIZE (GPR_CACHELINE_SIZE - 4) |
| #else |
| #error "Unknown architecture" |
| #endif |
| #endif |
| #if CL_CORE_LOCAL_BLOCK_PAD_SIZE > 0 |
| char padding[CL_CORE_LOCAL_BLOCK_PAD_SIZE]; |
| #endif |
| } cl_core_local_block; |
| |
| struct census_log { |
| int discard_old_records; |
| /* Number of cores (aka hardware-contexts) */ |
| unsigned num_cores; |
| /* number of CENSUS_LOG_2_MAX_RECORD_SIZE blocks in log */ |
| gpr_int32 num_blocks; |
| cl_block* blocks; /* Block metadata. */ |
| cl_core_local_block* core_local_blocks; /* Keeps core to block mappings. */ |
| gpr_mu lock; |
| int initialized; /* has log been initialized? */ |
| /* Keeps the state of the reader iterator. A value of 0 indicates that |
| iterator has reached the end. census_log_init_reader() resets the |
| value to num_core to restart iteration. */ |
| gpr_uint32 read_iterator_state; |
| /* Points to the block being read. If non-NULL, the block is locked for |
| reading (block_being_read_->reader_lock is held). */ |
| cl_block* block_being_read; |
| /* A non-zero value indicates that log is full. */ |
| gpr_atm is_full; |
| char* buffer; |
| cl_block_list free_block_list; |
| cl_block_list dirty_block_list; |
| gpr_atm out_of_space_count; |
| }; |
| |
| /* Single internal log */ |
| static struct census_log g_log; |
| |
| /* Functions that operate on an atomic memory location used as a lock */ |
| |
| /* Returns non-zero if lock is acquired */ |
| static int cl_try_lock(gpr_atm* lock) { return gpr_atm_acq_cas(lock, 0, 1); } |
| |
| static void cl_unlock(gpr_atm* lock) { gpr_atm_rel_store(lock, 0); } |
| |
| /* Functions that operate on cl_core_local_block's */ |
| |
| static void cl_core_local_block_set_block(cl_core_local_block* clb, |
| cl_block* block) { |
| gpr_atm_rel_store(&clb->block, (gpr_atm)block); |
| } |
| |
| static cl_block* cl_core_local_block_get_block(cl_core_local_block* clb) { |
| return (cl_block*)gpr_atm_acq_load(&clb->block); |
| } |
| |
| /* Functions that operate on cl_block_list_struct's */ |
| |
| static void cl_block_list_struct_initialize(cl_block_list_struct* bls, |
| cl_block* block) { |
| bls->next = bls->prev = bls; |
| bls->block = block; |
| } |
| |
| /* Functions that operate on cl_block_list's */ |
| |
| static void cl_block_list_initialize(cl_block_list* list) { |
| list->count = 0; |
| cl_block_list_struct_initialize(&list->ht, NULL); |
| } |
| |
| /* Returns head of *this, or NULL if empty. */ |
| static cl_block* cl_block_list_head(cl_block_list* list) { |
| return list->ht.next->block; |
| } |
| |
| /* Insert element *e after *pos. */ |
| static void cl_block_list_insert(cl_block_list* list, cl_block_list_struct* pos, |
| cl_block_list_struct* e) { |
| list->count++; |
| e->next = pos->next; |
| e->prev = pos; |
| e->next->prev = e; |
| e->prev->next = e; |
| } |
| |
| /* Insert block at the head of the list */ |
| static void cl_block_list_insert_at_head(cl_block_list* list, cl_block* block) { |
| cl_block_list_insert(list, &list->ht, &block->link); |
| } |
| |
| /* Insert block at the tail of the list */ |
| static void cl_block_list_insert_at_tail(cl_block_list* list, cl_block* block) { |
| cl_block_list_insert(list, list->ht.prev, &block->link); |
| } |
| |
| /* Removes block *b. Requires *b be in the list. */ |
| static void cl_block_list_remove(cl_block_list* list, cl_block* b) { |
| list->count--; |
| b->link.next->prev = b->link.prev; |
| b->link.prev->next = b->link.next; |
| } |
| |
| /* Functions that operate on cl_block's */ |
| |
| static void cl_block_initialize(cl_block* block, char* buffer) { |
| block->buffer = buffer; |
| gpr_atm_rel_store(&block->writer_lock, 0); |
| gpr_atm_rel_store(&block->reader_lock, 0); |
| gpr_atm_rel_store(&block->bytes_committed, 0); |
| block->bytes_read = 0; |
| cl_block_list_struct_initialize(&block->link, block); |
| } |
| |
| /* Guards against exposing partially written buffer to the reader. */ |
| static void cl_block_set_bytes_committed(cl_block* block, |
| gpr_int32 bytes_committed) { |
| gpr_atm_rel_store(&block->bytes_committed, bytes_committed); |
| } |
| |
| static gpr_int32 cl_block_get_bytes_committed(cl_block* block) { |
| return gpr_atm_acq_load(&block->bytes_committed); |
| } |
| |
| /* Tries to disable future read/write access to this block. Succeeds if: |
| - no in-progress write AND |
| - no in-progress read AND |
| - 'discard_data' set to true OR no unread data |
| On success, clears the block state and returns with writer_lock_ and |
| reader_lock_ held. These locks are released by a subsequent |
| cl_block_access_enable() call. */ |
| static int cl_block_try_disable_access(cl_block* block, int discard_data) { |
| if (!cl_try_lock(&block->writer_lock)) { |
| return 0; |
| } |
| if (!cl_try_lock(&block->reader_lock)) { |
| cl_unlock(&block->writer_lock); |
| return 0; |
| } |
| if (!discard_data && |
| (block->bytes_read != cl_block_get_bytes_committed(block))) { |
| cl_unlock(&block->reader_lock); |
| cl_unlock(&block->writer_lock); |
| return 0; |
| } |
| cl_block_set_bytes_committed(block, 0); |
| block->bytes_read = 0; |
| return 1; |
| } |
| |
| static void cl_block_enable_access(cl_block* block) { |
| cl_unlock(&block->reader_lock); |
| cl_unlock(&block->writer_lock); |
| } |
| |
| /* Returns with writer_lock held. */ |
| static void* cl_block_start_write(cl_block* block, size_t size) { |
| gpr_int32 bytes_committed; |
| if (!cl_try_lock(&block->writer_lock)) { |
| return NULL; |
| } |
| bytes_committed = cl_block_get_bytes_committed(block); |
| if (bytes_committed + size > CENSUS_LOG_MAX_RECORD_SIZE) { |
| cl_unlock(&block->writer_lock); |
| return NULL; |
| } |
| return block->buffer + bytes_committed; |
| } |
| |
| /* Releases writer_lock and increments committed bytes by 'bytes_written'. |
| 'bytes_written' must be <= 'size' specified in the corresponding |
| StartWrite() call. This function is thread-safe. */ |
| static void cl_block_end_write(cl_block* block, size_t bytes_written) { |
| cl_block_set_bytes_committed( |
| block, cl_block_get_bytes_committed(block) + bytes_written); |
| cl_unlock(&block->writer_lock); |
| } |
| |
| /* Returns a pointer to the first unread byte in buffer. The number of bytes |
| available are returned in 'bytes_available'. Acquires reader lock that is |
| released by a subsequent cl_block_end_read() call. Returns NULL if: |
| - read in progress |
| - no data available */ |
| static void* cl_block_start_read(cl_block* block, size_t* bytes_available) { |
| void* record; |
| if (!cl_try_lock(&block->reader_lock)) { |
| return NULL; |
| } |
| /* bytes_committed may change from under us. Use bytes_available to update |
| bytes_read below. */ |
| *bytes_available = cl_block_get_bytes_committed(block) - block->bytes_read; |
| if (*bytes_available == 0) { |
| cl_unlock(&block->reader_lock); |
| return NULL; |
| } |
| record = block->buffer + block->bytes_read; |
| block->bytes_read += *bytes_available; |
| return record; |
| } |
| |
| static void cl_block_end_read(cl_block* block) { |
| cl_unlock(&block->reader_lock); |
| } |
| |
| /* Internal functions operating on g_log */ |
| |
| /* Allocates a new free block (or recycles an available dirty block if log is |
| configured to discard old records). Returns NULL if out-of-space. */ |
| static cl_block* cl_allocate_block(void) { |
| cl_block* block = cl_block_list_head(&g_log.free_block_list); |
| if (block != NULL) { |
| cl_block_list_remove(&g_log.free_block_list, block); |
| return block; |
| } |
| if (!g_log.discard_old_records) { |
| /* No free block and log is configured to keep old records. */ |
| return NULL; |
| } |
| /* Recycle dirty block. Start from the oldest. */ |
| for (block = cl_block_list_head(&g_log.dirty_block_list); block != NULL; |
| block = block->link.next->block) { |
| if (cl_block_try_disable_access(block, 1 /* discard data */)) { |
| cl_block_list_remove(&g_log.dirty_block_list, block); |
| return block; |
| } |
| } |
| return NULL; |
| } |
| |
| /* Allocates a new block and updates core id => block mapping. 'old_block' |
| points to the block that the caller thinks is attached to |
| 'core_id'. 'old_block' may be NULL. Returns non-zero if: |
| - allocated a new block OR |
| - 'core_id' => 'old_block' mapping changed (another thread allocated a |
| block before lock was acquired). */ |
| static int cl_allocate_core_local_block(gpr_int32 core_id, |
| cl_block* old_block) { |
| /* Now that we have the lock, check if core-local mapping has changed. */ |
| cl_core_local_block* core_local_block = &g_log.core_local_blocks[core_id]; |
| cl_block* block = cl_core_local_block_get_block(core_local_block); |
| if ((block != NULL) && (block != old_block)) { |
| return 1; |
| } |
| if (block != NULL) { |
| cl_core_local_block_set_block(core_local_block, NULL); |
| cl_block_list_insert_at_tail(&g_log.dirty_block_list, block); |
| } |
| block = cl_allocate_block(); |
| if (block == NULL) { |
| gpr_atm_rel_store(&g_log.is_full, 1); |
| return 0; |
| } |
| cl_core_local_block_set_block(core_local_block, block); |
| cl_block_enable_access(block); |
| return 1; |
| } |
| |
| static cl_block* cl_get_block(void* record) { |
| gpr_uintptr p = (gpr_uintptr)((char*)record - g_log.buffer); |
| gpr_uintptr index = p >> CENSUS_LOG_2_MAX_RECORD_SIZE; |
| return &g_log.blocks[index]; |
| } |
| |
| /* Gets the next block to read and tries to free 'prev' block (if not NULL). |
| Returns NULL if reached the end. */ |
| static cl_block* cl_next_block_to_read(cl_block* prev) { |
| cl_block* block = NULL; |
| if (g_log.read_iterator_state == g_log.num_cores) { |
| /* We are traversing dirty list; find the next dirty block. */ |
| if (prev != NULL) { |
| /* Try to free the previous block if there is no unread data. This block |
| may have unread data if previously incomplete record completed between |
| read_next() calls. */ |
| block = prev->link.next->block; |
| if (cl_block_try_disable_access(prev, 0 /* do not discard data */)) { |
| cl_block_list_remove(&g_log.dirty_block_list, prev); |
| cl_block_list_insert_at_head(&g_log.free_block_list, prev); |
| gpr_atm_rel_store(&g_log.is_full, 0); |
| } |
| } else { |
| block = cl_block_list_head(&g_log.dirty_block_list); |
| } |
| if (block != NULL) { |
| return block; |
| } |
| /* We are done with the dirty list; moving on to core-local blocks. */ |
| } |
| while (g_log.read_iterator_state > 0) { |
| g_log.read_iterator_state--; |
| block = cl_core_local_block_get_block( |
| &g_log.core_local_blocks[g_log.read_iterator_state]); |
| if (block != NULL) { |
| return block; |
| } |
| } |
| return NULL; |
| } |
| |
| /* External functions: primary stats_log interface */ |
| void census_log_initialize(size_t size_in_mb, int discard_old_records) { |
| gpr_int32 ix; |
| /* Check cacheline alignment. */ |
| GPR_ASSERT(sizeof(cl_block) % GPR_CACHELINE_SIZE == 0); |
| GPR_ASSERT(sizeof(cl_core_local_block) % GPR_CACHELINE_SIZE == 0); |
| GPR_ASSERT(!g_log.initialized); |
| g_log.discard_old_records = discard_old_records; |
| g_log.num_cores = gpr_cpu_num_cores(); |
| /* Ensure at least as many blocks as there are cores. */ |
| g_log.num_blocks = GPR_MAX( |
| g_log.num_cores, (size_in_mb << 20) >> CENSUS_LOG_2_MAX_RECORD_SIZE); |
| gpr_mu_init(&g_log.lock); |
| g_log.read_iterator_state = 0; |
| g_log.block_being_read = NULL; |
| gpr_atm_rel_store(&g_log.is_full, 0); |
| g_log.core_local_blocks = (cl_core_local_block*)gpr_malloc_aligned( |
| g_log.num_cores * sizeof(cl_core_local_block), GPR_CACHELINE_SIZE_LOG); |
| memset(g_log.core_local_blocks, 0, |
| g_log.num_cores * sizeof(cl_core_local_block)); |
| g_log.blocks = (cl_block*)gpr_malloc_aligned( |
| g_log.num_blocks * sizeof(cl_block), GPR_CACHELINE_SIZE_LOG); |
| memset(g_log.blocks, 0, g_log.num_blocks * sizeof(cl_block)); |
| g_log.buffer = gpr_malloc(g_log.num_blocks * CENSUS_LOG_MAX_RECORD_SIZE); |
| memset(g_log.buffer, 0, g_log.num_blocks * CENSUS_LOG_MAX_RECORD_SIZE); |
| cl_block_list_initialize(&g_log.free_block_list); |
| cl_block_list_initialize(&g_log.dirty_block_list); |
| for (ix = 0; ix < g_log.num_blocks; ++ix) { |
| cl_block* block = g_log.blocks + ix; |
| cl_block_initialize(block, |
| g_log.buffer + (CENSUS_LOG_MAX_RECORD_SIZE * ix)); |
| cl_block_try_disable_access(block, 1 /* discard data */); |
| cl_block_list_insert_at_tail(&g_log.free_block_list, block); |
| } |
| gpr_atm_rel_store(&g_log.out_of_space_count, 0); |
| g_log.initialized = 1; |
| } |
| |
| void census_log_shutdown(void) { |
| GPR_ASSERT(g_log.initialized); |
| gpr_mu_destroy(&g_log.lock); |
| gpr_free_aligned(g_log.core_local_blocks); |
| g_log.core_local_blocks = NULL; |
| gpr_free_aligned(g_log.blocks); |
| g_log.blocks = NULL; |
| gpr_free(g_log.buffer); |
| g_log.buffer = NULL; |
| g_log.initialized = 0; |
| } |
| |
| void* census_log_start_write(size_t size) { |
| /* Used to bound number of times block allocation is attempted. */ |
| gpr_int32 attempts_remaining = g_log.num_blocks; |
| /* TODO(aveitch): move this inside the do loop when current_cpu is fixed */ |
| gpr_int32 core_id = gpr_cpu_current_cpu(); |
| GPR_ASSERT(g_log.initialized); |
| if (size > CENSUS_LOG_MAX_RECORD_SIZE) { |
| return NULL; |
| } |
| do { |
| int allocated; |
| void* record = NULL; |
| cl_block* block = |
| cl_core_local_block_get_block(&g_log.core_local_blocks[core_id]); |
| if (block && (record = cl_block_start_write(block, size))) { |
| return record; |
| } |
| /* Need to allocate a new block. We are here if: |
| - No block associated with the core OR |
| - Write in-progress on the block OR |
| - block is out of space */ |
| if (gpr_atm_acq_load(&g_log.is_full)) { |
| gpr_atm_no_barrier_fetch_add(&g_log.out_of_space_count, 1); |
| return NULL; |
| } |
| gpr_mu_lock(&g_log.lock); |
| allocated = cl_allocate_core_local_block(core_id, block); |
| gpr_mu_unlock(&g_log.lock); |
| if (!allocated) { |
| gpr_atm_no_barrier_fetch_add(&g_log.out_of_space_count, 1); |
| return NULL; |
| } |
| } while (attempts_remaining--); |
| /* Give up. */ |
| gpr_atm_no_barrier_fetch_add(&g_log.out_of_space_count, 1); |
| return NULL; |
| } |
| |
| void census_log_end_write(void* record, size_t bytes_written) { |
| GPR_ASSERT(g_log.initialized); |
| cl_block_end_write(cl_get_block(record), bytes_written); |
| } |
| |
| void census_log_init_reader(void) { |
| GPR_ASSERT(g_log.initialized); |
| gpr_mu_lock(&g_log.lock); |
| /* If a block is locked for reading unlock it. */ |
| if (g_log.block_being_read != NULL) { |
| cl_block_end_read(g_log.block_being_read); |
| g_log.block_being_read = NULL; |
| } |
| g_log.read_iterator_state = g_log.num_cores; |
| gpr_mu_unlock(&g_log.lock); |
| } |
| |
| const void* census_log_read_next(size_t* bytes_available) { |
| GPR_ASSERT(g_log.initialized); |
| gpr_mu_lock(&g_log.lock); |
| if (g_log.block_being_read != NULL) { |
| cl_block_end_read(g_log.block_being_read); |
| } |
| do { |
| g_log.block_being_read = cl_next_block_to_read(g_log.block_being_read); |
| if (g_log.block_being_read != NULL) { |
| void* record = |
| cl_block_start_read(g_log.block_being_read, bytes_available); |
| if (record != NULL) { |
| gpr_mu_unlock(&g_log.lock); |
| return record; |
| } |
| } |
| } while (g_log.block_being_read != NULL); |
| gpr_mu_unlock(&g_log.lock); |
| return NULL; |
| } |
| |
| size_t census_log_remaining_space(void) { |
| size_t space; |
| GPR_ASSERT(g_log.initialized); |
| gpr_mu_lock(&g_log.lock); |
| if (g_log.discard_old_records) { |
| /* Remaining space is not meaningful; just return the entire log space. */ |
| space = g_log.num_blocks << CENSUS_LOG_2_MAX_RECORD_SIZE; |
| } else { |
| space = g_log.free_block_list.count * CENSUS_LOG_MAX_RECORD_SIZE; |
| } |
| gpr_mu_unlock(&g_log.lock); |
| return space; |
| } |
| |
| int census_log_out_of_space_count(void) { |
| GPR_ASSERT(g_log.initialized); |
| return gpr_atm_acq_load(&g_log.out_of_space_count); |
| } |