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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,130 @@ | ||
| /* | ||
| * | ||
| * 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/support/stack_lockfree.h" | ||
|
|
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| #include <stdlib.h> | ||
| #include <string.h> | ||
|
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| #include <grpc/support/port_platform.h> | ||
| #include <grpc/support/alloc.h> | ||
| #include <grpc/support/atm.h> | ||
| #include <grpc/support/log.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 */ | ||
| gpr_uint16 index; | ||
| #ifdef GPR_ARCH_64 | ||
| gpr_uint16 pad; | ||
| gpr_uint32 aba_ctr; | ||
| #else | ||
| #ifdef GPR_ARCH_32 | ||
| gpr_uint16 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; | ||
|
|
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| #define ENTRY_ALIGNMENT_BITS 3 /* make sure that entries aligned to 8-bytes */ | ||
| #define INVALID_ENTRY_INDEX ((1<<16)-1) /* reserve this entry as invalid */ | ||
|
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| struct gpr_stack_lockfree { | ||
| lockfree_node *entries; | ||
| lockfree_node head; /* An atomic entry describing curr head */ | ||
| }; | ||
|
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||
| gpr_stack_lockfree *gpr_stack_lockfree_create(int entries) { | ||
| gpr_stack_lockfree *stack; | ||
| stack = 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 = gpr_malloc_aligned(entries * sizeof(stack->entries[0]), | ||
| ENTRY_ALIGNMENT_BITS); | ||
| /* Clear out all entries */ | ||
| memset(stack->entries, 0, entries * sizeof(stack->entries[0])); | ||
|
|
||
| /* Point the head at reserved dummy entry */ | ||
| stack->head.contents.index = INVALID_ENTRY_INDEX; | ||
| return stack; | ||
| } | ||
|
|
||
| void gpr_stack_lockfree_destroy(gpr_stack_lockfree *stack) { | ||
| gpr_free_aligned(stack->entries); | ||
| gpr_free(stack); | ||
| } | ||
|
|
||
| void gpr_stack_lockfree_push(gpr_stack_lockfree *stack, int entry) { | ||
| lockfree_node head; | ||
| lockfree_node newhead; | ||
|
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| /* First fill in the entry's index and aba ctr for new head */ | ||
| newhead.contents.index = (gpr_uint16)entry; | ||
| /* Also post-increment the aba_ctr */ | ||
| newhead.contents.aba_ctr = stack->entries[entry].contents.aba_ctr++; | ||
|
|
||
| do { | ||
| /* Atomically get the existing head value for use */ | ||
| head.atm = gpr_atm_no_barrier_load(&(stack->head.atm)); | ||
| /* Point to it */ | ||
| stack->entries[entry].contents.index = head.contents.index; | ||
| } 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 */ | ||
| } | ||
|
|
||
| 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.contents.index = stack->entries[head.contents.index].contents.index; | ||
|
|
||
| } while (!gpr_atm_no_barrier_cas(&(stack->head.atm), | ||
| head.atm, | ||
| newhead.atm)); | ||
| return newhead.contents.index; | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,50 @@ | ||
| /* | ||
| * | ||
| * 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. | ||
| * | ||
| */ | ||
|
|
||
| #ifndef GRPC_INTERNAL_CORE_SUPPORT_STACK_LOCKFREE_H | ||
| #define GRPC_INTERNAL_CORE_SUPPORT_STACK_LOCKFREE_H | ||
|
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| typedef struct gpr_stack_lockfree gpr_stack_lockfree; | ||
|
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| /* This stack must specify the maximum number of entries to track. | ||
| The current implementation only allows up to 65534 entries */ | ||
| gpr_stack_lockfree *gpr_stack_lockfree_create(int entries); | ||
| void gpr_stack_lockfree_destroy(gpr_stack_lockfree *); | ||
|
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| /* Pass in a valid entry number for the next stack entry */ | ||
| void gpr_stack_lockfree_push(gpr_stack_lockfree *, int entry); | ||
|
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| /* Returns -1 on empty or the actual entry number */ | ||
| int gpr_stack_lockfree_pop(gpr_stack_lockfree *); | ||
|
|
||
| #endif /* GRPC_INTERNAL_CORE_SUPPORT_STACK_LOCKFREE_H */ |
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