diff options
author | Nicolas "Pixel" Noble <pixel@nobis-crew.org> | 2017-06-26 22:01:11 +0200 |
---|---|---|
committer | Nicolas "Pixel" Noble <pixel@nobis-crew.org> | 2017-06-26 22:01:11 +0200 |
commit | 5d80dc4985ef01a468e027df75912bfc1e95579d (patch) | |
tree | 17bf626f6c6709661435924a74ada235e777c221 /src/core/lib/support/stack_lockfree.c | |
parent | e7c2458d66b4e4210fb4c5d7e1670aef6b4c9381 (diff) | |
parent | 8bec6a93163861e467005a23c997eb93b793710b (diff) |
Merge branch 'master' of https://github.com/grpc/grpc into import
Diffstat (limited to 'src/core/lib/support/stack_lockfree.c')
-rw-r--r-- | src/core/lib/support/stack_lockfree.c | 152 |
1 files changed, 0 insertions, 152 deletions
diff --git a/src/core/lib/support/stack_lockfree.c b/src/core/lib/support/stack_lockfree.c deleted file mode 100644 index dfbd3fb125..0000000000 --- a/src/core/lib/support/stack_lockfree.c +++ /dev/null @@ -1,152 +0,0 @@ -/* - * - * 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. - * - */ - -#include "src/core/lib/support/stack_lockfree.h" - -#include <stdlib.h> -#include <string.h> - -#include <grpc/support/alloc.h> -#include <grpc/support/atm.h> -#include <grpc/support/log.h> -#include <grpc/support/port_platform.h> - -/* The lockfree node structure is a single architecture-level - word that allows for an atomic CAS to set it up. */ -struct lockfree_node_contents { - /* next thing to look at. Actual index for head, next index otherwise */ - uint16_t index; -#ifdef GPR_ARCH_64 - uint16_t pad; - uint32_t aba_ctr; -#else -#ifdef GPR_ARCH_32 - uint16_t aba_ctr; -#else -#error Unsupported bit width architecture -#endif -#endif -}; - -/* Use a union to make sure that these are in the same bits as an atm word */ -typedef union lockfree_node { - gpr_atm atm; - struct lockfree_node_contents contents; -} lockfree_node; - -/* make sure that entries aligned to 8-bytes */ -#define ENTRY_ALIGNMENT_BITS 3 -/* reserve this entry as invalid */ -#define INVALID_ENTRY_INDEX ((1 << 16) - 1) - -struct gpr_stack_lockfree { - lockfree_node *entries; - lockfree_node head; /* An atomic entry describing curr head */ -}; - -gpr_stack_lockfree *gpr_stack_lockfree_create(size_t entries) { - gpr_stack_lockfree *stack; - stack = (gpr_stack_lockfree *)gpr_malloc(sizeof(*stack)); - /* Since we only allocate 16 bits to represent an entry number, - * make sure that we are within the desired range */ - /* Reserve the highest entry number as a dummy */ - GPR_ASSERT(entries < INVALID_ENTRY_INDEX); - stack->entries = (lockfree_node *)gpr_malloc_aligned( - entries * sizeof(stack->entries[0]), ENTRY_ALIGNMENT_BITS); - /* Clear out all entries */ - memset(stack->entries, 0, entries * sizeof(stack->entries[0])); - memset(&stack->head, 0, sizeof(stack->head)); - - GPR_ASSERT(sizeof(stack->entries->atm) == sizeof(stack->entries->contents)); - - /* Point the head at reserved dummy entry */ - stack->head.contents.index = INVALID_ENTRY_INDEX; -/* Fill in the pad and aba_ctr to avoid confusing memcheck tools */ -#ifdef GPR_ARCH_64 - stack->head.contents.pad = 0; -#endif - stack->head.contents.aba_ctr = 0; - return stack; -} - -void gpr_stack_lockfree_destroy(gpr_stack_lockfree *stack) { - gpr_free_aligned(stack->entries); - gpr_free(stack); -} - -int gpr_stack_lockfree_push(gpr_stack_lockfree *stack, int entry) { - lockfree_node head; - lockfree_node newhead; - lockfree_node curent; - lockfree_node newent; - - /* First fill in the entry's index and aba ctr for new head */ - newhead.contents.index = (uint16_t)entry; -#ifdef GPR_ARCH_64 - /* Fill in the pad to avoid confusing memcheck tools */ - newhead.contents.pad = 0; -#endif - - /* Also post-increment the aba_ctr */ - curent.atm = gpr_atm_no_barrier_load(&stack->entries[entry].atm); - newhead.contents.aba_ctr = ++curent.contents.aba_ctr; - gpr_atm_no_barrier_store(&stack->entries[entry].atm, curent.atm); - - do { - /* Atomically get the existing head value for use */ - head.atm = gpr_atm_no_barrier_load(&(stack->head.atm)); - /* Point to it */ - newent.atm = gpr_atm_no_barrier_load(&stack->entries[entry].atm); - newent.contents.index = head.contents.index; - gpr_atm_no_barrier_store(&stack->entries[entry].atm, newent.atm); - } while (!gpr_atm_rel_cas(&(stack->head.atm), head.atm, newhead.atm)); - /* Use rel_cas above to make sure that entry index is set properly */ - return head.contents.index == INVALID_ENTRY_INDEX; -} - -int gpr_stack_lockfree_pop(gpr_stack_lockfree *stack) { - lockfree_node head; - lockfree_node newhead; - - do { - head.atm = gpr_atm_acq_load(&(stack->head.atm)); - if (head.contents.index == INVALID_ENTRY_INDEX) { - return -1; - } - newhead.atm = - gpr_atm_no_barrier_load(&(stack->entries[head.contents.index].atm)); - - } while (!gpr_atm_no_barrier_cas(&(stack->head.atm), head.atm, newhead.atm)); - - return head.contents.index; -} |