From c69cb8cc094cc916adbc516b09e944cd3d137c01 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 27 Apr 2024 13:08:07 +0200 Subject: Adding upstream version 1.29.3. Signed-off-by: Daniel Baumann --- database/engine/rrdenglocking.c | 241 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 241 insertions(+) create mode 100644 database/engine/rrdenglocking.c (limited to 'database/engine/rrdenglocking.c') diff --git a/database/engine/rrdenglocking.c b/database/engine/rrdenglocking.c new file mode 100644 index 0000000..a23abf3 --- /dev/null +++ b/database/engine/rrdenglocking.c @@ -0,0 +1,241 @@ +// SPDX-License-Identifier: GPL-3.0-or-later +#include "rrdengine.h" + +struct page_cache_descr *rrdeng_create_pg_cache_descr(struct rrdengine_instance *ctx) +{ + struct page_cache_descr *pg_cache_descr; + + pg_cache_descr = mallocz(sizeof(*pg_cache_descr)); + rrd_stat_atomic_add(&ctx->stats.page_cache_descriptors, 1); + pg_cache_descr->page = NULL; + pg_cache_descr->flags = 0; + pg_cache_descr->prev = pg_cache_descr->next = NULL; + pg_cache_descr->refcnt = 0; + pg_cache_descr->waiters = 0; + fatal_assert(0 == uv_cond_init(&pg_cache_descr->cond)); + fatal_assert(0 == uv_mutex_init(&pg_cache_descr->mutex)); + + return pg_cache_descr; +} + +void rrdeng_destroy_pg_cache_descr(struct rrdengine_instance *ctx, struct page_cache_descr *pg_cache_descr) +{ + uv_cond_destroy(&pg_cache_descr->cond); + uv_mutex_destroy(&pg_cache_descr->mutex); + freez(pg_cache_descr); + rrd_stat_atomic_add(&ctx->stats.page_cache_descriptors, -1); +} + +/* also allocates page cache descriptor if missing */ +void rrdeng_page_descr_mutex_lock(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr) +{ + unsigned long old_state, old_users, new_state, ret_state; + struct page_cache_descr *pg_cache_descr = NULL; + uint8_t we_locked; + + we_locked = 0; + while (1) { /* spin */ + old_state = descr->pg_cache_descr_state; + old_users = old_state >> PG_CACHE_DESCR_SHIFT; + + if (unlikely(we_locked)) { + fatal_assert(old_state & PG_CACHE_DESCR_LOCKED); + new_state = (1 << PG_CACHE_DESCR_SHIFT) | PG_CACHE_DESCR_ALLOCATED; + ret_state = ulong_compare_and_swap(&descr->pg_cache_descr_state, old_state, new_state); + if (old_state == ret_state) { + /* success */ + break; + } + continue; /* spin */ + } + if (old_state & PG_CACHE_DESCR_LOCKED) { + fatal_assert(0 == old_users); + continue; /* spin */ + } + if (0 == old_state) { + /* no page cache descriptor has been allocated */ + + if (NULL == pg_cache_descr) { + pg_cache_descr = rrdeng_create_pg_cache_descr(ctx); + } + new_state = PG_CACHE_DESCR_LOCKED; + ret_state = ulong_compare_and_swap(&descr->pg_cache_descr_state, 0, new_state); + if (0 == ret_state) { + we_locked = 1; + descr->pg_cache_descr = pg_cache_descr; + pg_cache_descr->descr = descr; + pg_cache_descr = NULL; /* make sure we don't free pg_cache_descr */ + /* retry */ + continue; + } + continue; /* spin */ + } + /* page cache descriptor is already allocated */ + if (unlikely(!(old_state & PG_CACHE_DESCR_ALLOCATED))) { + fatal("Invalid page cache descriptor locking state:%#lX", old_state); + } + new_state = (old_users + 1) << PG_CACHE_DESCR_SHIFT; + new_state |= old_state & PG_CACHE_DESCR_FLAGS_MASK; + + ret_state = ulong_compare_and_swap(&descr->pg_cache_descr_state, old_state, new_state); + if (old_state == ret_state) { + /* success */ + break; + } + /* spin */ + } + + if (pg_cache_descr) { + rrdeng_destroy_pg_cache_descr(ctx, pg_cache_descr); + } + pg_cache_descr = descr->pg_cache_descr; + uv_mutex_lock(&pg_cache_descr->mutex); +} + +void rrdeng_page_descr_mutex_unlock(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr) +{ + unsigned long old_state, new_state, ret_state, old_users; + struct page_cache_descr *pg_cache_descr, *delete_pg_cache_descr = NULL; + uint8_t we_locked; + + uv_mutex_unlock(&descr->pg_cache_descr->mutex); + + we_locked = 0; + while (1) { /* spin */ + old_state = descr->pg_cache_descr_state; + old_users = old_state >> PG_CACHE_DESCR_SHIFT; + + if (unlikely(we_locked)) { + fatal_assert(0 == old_users); + + ret_state = ulong_compare_and_swap(&descr->pg_cache_descr_state, old_state, 0); + if (old_state == ret_state) { + /* success */ + rrdeng_destroy_pg_cache_descr(ctx, delete_pg_cache_descr); + return; + } + continue; /* spin */ + } + if (old_state & PG_CACHE_DESCR_LOCKED) { + fatal_assert(0 == old_users); + continue; /* spin */ + } + fatal_assert(old_state & PG_CACHE_DESCR_ALLOCATED); + pg_cache_descr = descr->pg_cache_descr; + /* caller is the only page cache descriptor user and there are no pending references on the page */ + if ((old_state & PG_CACHE_DESCR_DESTROY) && (1 == old_users) && + !pg_cache_descr->flags && !pg_cache_descr->refcnt) { + fatal_assert(!pg_cache_descr->waiters); + + new_state = PG_CACHE_DESCR_LOCKED; + ret_state = ulong_compare_and_swap(&descr->pg_cache_descr_state, old_state, new_state); + if (old_state == ret_state) { + we_locked = 1; + delete_pg_cache_descr = pg_cache_descr; + descr->pg_cache_descr = NULL; + /* retry */ + continue; + } + continue; /* spin */ + } + fatal_assert(old_users > 0); + new_state = (old_users - 1) << PG_CACHE_DESCR_SHIFT; + new_state |= old_state & PG_CACHE_DESCR_FLAGS_MASK; + + ret_state = ulong_compare_and_swap(&descr->pg_cache_descr_state, old_state, new_state); + if (old_state == ret_state) { + /* success */ + break; + } + /* spin */ + } +} + +/* + * Tries to deallocate page cache descriptor. If it fails, it postpones deallocation by setting the + * PG_CACHE_DESCR_DESTROY flag which will be eventually cleared by a different context after doing + * the deallocation. + */ +void rrdeng_try_deallocate_pg_cache_descr(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr) +{ + unsigned long old_state, new_state, ret_state, old_users; + struct page_cache_descr *pg_cache_descr = NULL; + uint8_t just_locked, can_free, must_unlock; + + just_locked = 0; + can_free = 0; + must_unlock = 0; + while (1) { /* spin */ + old_state = descr->pg_cache_descr_state; + old_users = old_state >> PG_CACHE_DESCR_SHIFT; + + if (unlikely(just_locked)) { + fatal_assert(0 == old_users); + + must_unlock = 1; + just_locked = 0; + /* Try deallocate if there are no pending references on the page */ + if (!pg_cache_descr->flags && !pg_cache_descr->refcnt) { + fatal_assert(!pg_cache_descr->waiters); + + descr->pg_cache_descr = NULL; + can_free = 1; + /* success */ + continue; + } + continue; /* spin */ + } + if (unlikely(must_unlock)) { + fatal_assert(0 == old_users); + + if (can_free) { + /* success */ + new_state = 0; + } else { + new_state = old_state | PG_CACHE_DESCR_DESTROY; + new_state &= ~PG_CACHE_DESCR_LOCKED; + } + ret_state = ulong_compare_and_swap(&descr->pg_cache_descr_state, old_state, new_state); + if (old_state == ret_state) { + /* unlocked */ + if (can_free) + rrdeng_destroy_pg_cache_descr(ctx, pg_cache_descr); + return; + } + continue; /* spin */ + } + if (!(old_state & PG_CACHE_DESCR_ALLOCATED)) { + /* don't do anything */ + return; + } + if (old_state & PG_CACHE_DESCR_LOCKED) { + fatal_assert(0 == old_users); + continue; /* spin */ + } + /* caller is the only page cache descriptor user */ + if (0 == old_users) { + new_state = old_state | PG_CACHE_DESCR_LOCKED; + ret_state = ulong_compare_and_swap(&descr->pg_cache_descr_state, old_state, new_state); + if (old_state == ret_state) { + just_locked = 1; + pg_cache_descr = descr->pg_cache_descr; + /* retry */ + continue; + } + continue; /* spin */ + } + if (old_state & PG_CACHE_DESCR_DESTROY) { + /* don't do anything */ + return; + } + /* plant PG_CACHE_DESCR_DESTROY so that other contexts eventually free the page cache descriptor */ + new_state = old_state | PG_CACHE_DESCR_DESTROY; + + ret_state = ulong_compare_and_swap(&descr->pg_cache_descr_state, old_state, new_state); + if (old_state == ret_state) { + /* success */ + return; + } + /* spin */ + } +} \ No newline at end of file -- cgit v1.2.3