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Diffstat (limited to 'src/core/ext/census/census_log.cc')
| -rw-r--r-- | src/core/ext/census/census_log.cc | 588 |
1 files changed, 0 insertions, 588 deletions
diff --git a/src/core/ext/census/census_log.cc b/src/core/ext/census/census_log.cc deleted file mode 100644 index 100047f12b..0000000000 --- a/src/core/ext/census/census_log.cc +++ /dev/null @@ -1,588 +0,0 @@ -/* - * - * Copyright 2015 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. - * - */ - -/* 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/ext/census/census_log.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> -#include <string.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 */ - int32_t 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 - int32_t 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 { - int32_t 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 */ - int32_t 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. */ - uint32_t 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, - int32_t bytes_committed) { - gpr_atm_rel_store(&block->bytes_committed, bytes_committed); -} - -static int32_t 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) { - int32_t 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(int32_t 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) { - uintptr_t p = (uintptr_t)((char *)record - g_log.buffer); - uintptr_t 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) { - int32_t 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. */ - int32_t attempts_remaining = g_log.num_blocks; - /* TODO(aveitch): move this inside the do loop when current_cpu is fixed */ - int32_t 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); -} |