Import CK as of commit 6b141c0bdd21ce8b3e14147af8f87f22b20ecf32
This brings us changes we needed in ck_epoch.
This commit is contained in:
Olivier Houchard
parent
c1411a76e5
commit
7e8cd4e1af
@ -105,7 +105,7 @@ linux_rcu_runtime_init(void *arg __unused)
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ck_epoch_record_t *record;
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record = malloc(sizeof(*record), M_LRCU, M_WAITOK | M_ZERO);
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ck_epoch_register(&linux_epoch, record);
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ck_epoch_register(&linux_epoch, record, NULL);
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DPCPU_ID_SET(i, linux_reader_epoch_record, record);
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}
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@ -116,7 +116,7 @@ linux_rcu_runtime_init(void *arg __unused)
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record = malloc(sizeof(*record), M_LRCU, M_WAITOK | M_ZERO);
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ck_epoch_register(&linux_epoch, &record->epoch_record);
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ck_epoch_register(&linux_epoch, &record->epoch_record, NULL);
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mtx_init(&record->head_lock, "LRCU-HEAD", NULL, MTX_DEF);
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mtx_init(&record->sync_lock, "LRCU-SYNC", NULL, MTX_DEF);
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TASK_INIT(&record->task, 0, linux_rcu_cleaner_func, record);
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@ -170,14 +170,14 @@ linux_srcu_get_record(void)
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* NOTE: The only records that are unregistered and can be
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* recycled are srcu_epoch_records.
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*/
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record = (struct srcu_epoch_record *)ck_epoch_recycle(&linux_epoch);
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record = (struct srcu_epoch_record *)ck_epoch_recycle(&linux_epoch, NULL);
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if (__predict_true(record != NULL))
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return (record);
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record = malloc(sizeof(*record), M_LRCU, M_WAITOK | M_ZERO);
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mtx_init(&record->read_lock, "SRCU-READ", NULL, MTX_DEF | MTX_NOWITNESS);
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mtx_init(&record->sync_lock, "SRCU-SYNC", NULL, MTX_DEF | MTX_NOWITNESS);
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ck_epoch_register(&linux_epoch, &record->epoch_record);
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ck_epoch_register(&linux_epoch, &record->epoch_record, NULL);
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return (record);
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}
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@ -83,6 +83,7 @@ struct ck_epoch_ref {
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};
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struct ck_epoch_record {
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ck_stack_entry_t record_next;
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struct ck_epoch *global;
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unsigned int state;
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unsigned int epoch;
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@ -92,17 +93,16 @@ struct ck_epoch_record {
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} local CK_CC_CACHELINE;
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unsigned int n_pending;
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unsigned int n_peak;
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unsigned long n_dispatch;
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unsigned int n_dispatch;
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void *ct;
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ck_stack_t pending[CK_EPOCH_LENGTH];
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ck_stack_entry_t record_next;
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} CK_CC_CACHELINE;
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typedef struct ck_epoch_record ck_epoch_record_t;
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struct ck_epoch {
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unsigned int epoch;
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char pad[CK_MD_CACHELINE - sizeof(unsigned int)];
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ck_stack_t records;
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unsigned int n_free;
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ck_stack_t records;
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};
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typedef struct ck_epoch ck_epoch_t;
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@ -110,7 +110,14 @@ typedef struct ck_epoch ck_epoch_t;
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* Internal functions.
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*/
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void _ck_epoch_addref(ck_epoch_record_t *, ck_epoch_section_t *);
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void _ck_epoch_delref(ck_epoch_record_t *, ck_epoch_section_t *);
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bool _ck_epoch_delref(ck_epoch_record_t *, ck_epoch_section_t *);
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CK_CC_FORCE_INLINE static void *
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ck_epoch_record_ct(const ck_epoch_record_t *record)
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{
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return ck_pr_load_ptr(&record->ct);
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}
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/*
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* Marks the beginning of an epoch-protected section.
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@ -160,9 +167,10 @@ ck_epoch_begin(ck_epoch_record_t *record, ck_epoch_section_t *section)
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}
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/*
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* Marks the end of an epoch-protected section.
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* Marks the end of an epoch-protected section. Returns true if no more
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* sections exist for the caller.
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*/
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CK_CC_FORCE_INLINE static void
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CK_CC_FORCE_INLINE static bool
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ck_epoch_end(ck_epoch_record_t *record, ck_epoch_section_t *section)
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{
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@ -170,15 +178,19 @@ ck_epoch_end(ck_epoch_record_t *record, ck_epoch_section_t *section)
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ck_pr_store_uint(&record->active, record->active - 1);
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if (section != NULL)
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_ck_epoch_delref(record, section);
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return _ck_epoch_delref(record, section);
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return;
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return record->active == 0;
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}
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/*
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* Defers the execution of the function pointed to by the "cb"
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* argument until an epoch counter loop. This allows for a
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* non-blocking deferral.
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*
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* We can get away without a fence here due to the monotonic nature
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* of the epoch counter. Worst case, this will result in some delays
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* before object destruction.
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*/
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CK_CC_FORCE_INLINE static void
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ck_epoch_call(ck_epoch_record_t *record,
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@ -195,13 +207,74 @@ ck_epoch_call(ck_epoch_record_t *record,
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return;
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}
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/*
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* Same as ck_epoch_call, but allows for records to be shared and is reentrant.
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*/
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CK_CC_FORCE_INLINE static void
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ck_epoch_call_strict(ck_epoch_record_t *record,
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ck_epoch_entry_t *entry,
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ck_epoch_cb_t *function)
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{
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struct ck_epoch *epoch = record->global;
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unsigned int e = ck_pr_load_uint(&epoch->epoch);
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unsigned int offset = e & (CK_EPOCH_LENGTH - 1);
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ck_pr_inc_uint(&record->n_pending);
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entry->function = function;
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/* Store fence is implied by push operation. */
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ck_stack_push_upmc(&record->pending[offset], &entry->stack_entry);
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return;
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}
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/*
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* This callback is used for synchronize_wait to allow for custom blocking
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* behavior.
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*/
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typedef void ck_epoch_wait_cb_t(ck_epoch_t *, ck_epoch_record_t *,
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void *);
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/*
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* Return latest epoch value. This operation provides load ordering.
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*/
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CK_CC_FORCE_INLINE static unsigned int
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ck_epoch_value(const ck_epoch_t *ep)
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{
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ck_pr_fence_load();
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return ck_pr_load_uint(&ep->epoch);
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}
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void ck_epoch_init(ck_epoch_t *);
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ck_epoch_record_t *ck_epoch_recycle(ck_epoch_t *);
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void ck_epoch_register(ck_epoch_t *, ck_epoch_record_t *);
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/*
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* Attempts to recycle an unused epoch record. If one is successfully
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* allocated, the record context pointer is also updated.
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*/
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ck_epoch_record_t *ck_epoch_recycle(ck_epoch_t *, void *);
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/*
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* Registers an epoch record. An optional context pointer may be passed that
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* is retrievable with ck_epoch_record_ct.
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*/
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void ck_epoch_register(ck_epoch_t *, ck_epoch_record_t *, void *);
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/*
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* Marks a record as available for re-use by a subsequent recycle operation.
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* Note that the record cannot be physically destroyed.
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*/
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void ck_epoch_unregister(ck_epoch_record_t *);
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bool ck_epoch_poll(ck_epoch_record_t *);
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void ck_epoch_synchronize(ck_epoch_record_t *);
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void ck_epoch_synchronize_wait(ck_epoch_t *, ck_epoch_wait_cb_t *, void *);
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void ck_epoch_barrier(ck_epoch_record_t *);
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void ck_epoch_barrier_wait(ck_epoch_record_t *, ck_epoch_wait_cb_t *, void *);
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/*
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* Reclaim entries associated with a record. This is safe to call only on
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* the caller's record or records that are using call_strict.
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*/
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void ck_epoch_reclaim(ck_epoch_record_t *);
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#endif /* CK_EPOCH_H */
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@ -139,7 +139,7 @@ CK_STACK_CONTAINER(struct ck_epoch_entry, stack_entry,
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#define CK_EPOCH_SENSE_MASK (CK_EPOCH_SENSE - 1)
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void
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bool
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_ck_epoch_delref(struct ck_epoch_record *record,
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struct ck_epoch_section *section)
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{
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@ -150,7 +150,7 @@ _ck_epoch_delref(struct ck_epoch_record *record,
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current->count--;
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if (current->count > 0)
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return;
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return false;
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/*
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* If the current bucket no longer has any references, then
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@ -161,8 +161,7 @@ _ck_epoch_delref(struct ck_epoch_record *record,
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* If no other active bucket exists, then the record will go
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* inactive in order to allow for forward progress.
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*/
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other = &record->local.bucket[(i + 1) &
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CK_EPOCH_SENSE_MASK];
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other = &record->local.bucket[(i + 1) & CK_EPOCH_SENSE_MASK];
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if (other->count > 0 &&
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((int)(current->epoch - other->epoch) < 0)) {
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/*
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@ -172,7 +171,7 @@ _ck_epoch_delref(struct ck_epoch_record *record,
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ck_pr_store_uint(&record->epoch, other->epoch);
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}
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return;
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return true;
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}
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void
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@ -230,7 +229,7 @@ ck_epoch_init(struct ck_epoch *global)
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}
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struct ck_epoch_record *
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ck_epoch_recycle(struct ck_epoch *global)
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ck_epoch_recycle(struct ck_epoch *global, void *ct)
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{
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struct ck_epoch_record *record;
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ck_stack_entry_t *cursor;
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@ -249,6 +248,12 @@ ck_epoch_recycle(struct ck_epoch *global)
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CK_EPOCH_STATE_USED);
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if (state == CK_EPOCH_STATE_FREE) {
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ck_pr_dec_uint(&global->n_free);
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ck_pr_store_ptr(&record->ct, ct);
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/*
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* The context pointer is ordered by a
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* subsequent protected section.
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*/
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return record;
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}
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}
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@ -258,7 +263,8 @@ ck_epoch_recycle(struct ck_epoch *global)
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}
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void
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ck_epoch_register(struct ck_epoch *global, struct ck_epoch_record *record)
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ck_epoch_register(struct ck_epoch *global, struct ck_epoch_record *record,
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void *ct)
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{
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size_t i;
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@ -269,6 +275,7 @@ ck_epoch_register(struct ck_epoch *global, struct ck_epoch_record *record)
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record->n_dispatch = 0;
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record->n_peak = 0;
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record->n_pending = 0;
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record->ct = ct;
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memset(&record->local, 0, sizeof record->local);
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for (i = 0; i < CK_EPOCH_LENGTH; i++)
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@ -295,6 +302,7 @@ ck_epoch_unregister(struct ck_epoch_record *record)
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for (i = 0; i < CK_EPOCH_LENGTH; i++)
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ck_stack_init(&record->pending[i]);
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ck_pr_store_ptr(&record->ct, NULL);
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ck_pr_fence_store();
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ck_pr_store_uint(&record->state, CK_EPOCH_STATE_FREE);
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ck_pr_inc_uint(&global->n_free);
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@ -345,11 +353,10 @@ ck_epoch_dispatch(struct ck_epoch_record *record, unsigned int e)
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{
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unsigned int epoch = e & (CK_EPOCH_LENGTH - 1);
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ck_stack_entry_t *head, *next, *cursor;
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unsigned int n_pending, n_peak;
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unsigned int i = 0;
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head = CK_STACK_FIRST(&record->pending[epoch]);
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ck_stack_init(&record->pending[epoch]);
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head = ck_stack_batch_pop_upmc(&record->pending[epoch]);
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for (cursor = head; cursor != NULL; cursor = next) {
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struct ck_epoch_entry *entry =
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ck_epoch_entry_container(cursor);
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@ -359,11 +366,18 @@ ck_epoch_dispatch(struct ck_epoch_record *record, unsigned int e)
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i++;
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}
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if (record->n_pending > record->n_peak)
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record->n_peak = record->n_pending;
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n_peak = ck_pr_load_uint(&record->n_peak);
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n_pending = ck_pr_load_uint(&record->n_pending);
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/* We don't require accuracy around peak calculation. */
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if (n_pending > n_peak)
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ck_pr_store_uint(&record->n_peak, n_peak);
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if (i > 0) {
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ck_pr_add_uint(&record->n_dispatch, i);
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ck_pr_sub_uint(&record->n_pending, i);
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}
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record->n_dispatch += i;
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record->n_pending -= i;
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return;
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}
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@ -381,13 +395,24 @@ ck_epoch_reclaim(struct ck_epoch_record *record)
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return;
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}
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CK_CC_FORCE_INLINE static void
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epoch_block(struct ck_epoch *global, struct ck_epoch_record *cr,
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ck_epoch_wait_cb_t *cb, void *ct)
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{
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if (cb != NULL)
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cb(global, cr, ct);
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return;
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}
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/*
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* This function must not be called with-in read section.
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*/
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void
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ck_epoch_synchronize(struct ck_epoch_record *record)
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ck_epoch_synchronize_wait(struct ck_epoch *global,
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ck_epoch_wait_cb_t *cb, void *ct)
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{
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struct ck_epoch *global = record->global;
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struct ck_epoch_record *cr;
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unsigned int delta, epoch, goal, i;
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bool active;
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@ -424,10 +449,27 @@ ck_epoch_synchronize(struct ck_epoch_record *record)
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* period.
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*/
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e_d = ck_pr_load_uint(&global->epoch);
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if (e_d != delta) {
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delta = e_d;
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goto reload;
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if (e_d == delta) {
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epoch_block(global, cr, cb, ct);
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continue;
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}
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/*
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* If the epoch has been updated, we may have already
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* met our goal.
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*/
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delta = e_d;
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if ((goal > epoch) & (delta >= goal))
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goto leave;
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epoch_block(global, cr, cb, ct);
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/*
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* If the epoch has been updated, then a grace period
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* requires that all threads are observed idle at the
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* same epoch.
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*/
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cr = NULL;
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}
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/*
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@ -459,20 +501,6 @@ ck_epoch_synchronize(struct ck_epoch_record *record)
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* Otherwise, we have just acquired latest snapshot.
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*/
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delta = delta + r;
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continue;
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reload:
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if ((goal > epoch) & (delta >= goal)) {
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/*
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* Right now, epoch overflow is handled as an edge
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* case. If we have already observed an epoch
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* generation, then we can be sure no hazardous
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* references exist to objects from this generation. We
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* can actually avoid an addtional scan step at this
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* point.
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*/
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break;
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}
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}
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/*
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@ -480,8 +508,16 @@ ck_epoch_synchronize(struct ck_epoch_record *record)
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* However, if non-temporal instructions are used, full barrier
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* semantics are necessary.
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*/
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leave:
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ck_pr_fence_memory();
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record->epoch = delta;
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return;
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}
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void
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ck_epoch_synchronize(struct ck_epoch_record *record)
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{
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ck_epoch_synchronize_wait(record->global, NULL, NULL);
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return;
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}
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@ -494,6 +530,16 @@ ck_epoch_barrier(struct ck_epoch_record *record)
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return;
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}
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void
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ck_epoch_barrier_wait(struct ck_epoch_record *record, ck_epoch_wait_cb_t *cb,
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void *ct)
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{
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ck_epoch_synchronize_wait(record->global, cb, ct);
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ck_epoch_reclaim(record);
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return;
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}
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/*
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* It may be worth it to actually apply these deferral semantics to an epoch
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* that was observed at ck_epoch_call time. The problem is that the latter
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@ -509,7 +555,6 @@ ck_epoch_poll(struct ck_epoch_record *record)
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{
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bool active;
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unsigned int epoch;
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unsigned int snapshot;
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struct ck_epoch_record *cr = NULL;
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struct ck_epoch *global = record->global;
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@ -533,12 +578,7 @@ ck_epoch_poll(struct ck_epoch_record *record)
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}
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/* If an active thread exists, rely on epoch observation. */
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if (ck_pr_cas_uint_value(&global->epoch, epoch, epoch + 1,
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&snapshot) == false) {
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record->epoch = snapshot;
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} else {
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record->epoch = epoch + 1;
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}
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(void)ck_pr_cas_uint(&global->epoch, epoch, epoch + 1);
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||||
|
||||
ck_epoch_dispatch(record, epoch + 1);
|
||||
return true;
|
||||
|
||||
Loading…
Reference in New Issue
Block a user