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Diffstat (limited to 'database/engine/pagecache.h')
| -rw-r--r-- | database/engine/pagecache.h | 231 |
1 files changed, 231 insertions, 0 deletions
diff --git a/database/engine/pagecache.h b/database/engine/pagecache.h new file mode 100644 index 0000000..31e9739 --- /dev/null +++ b/database/engine/pagecache.h @@ -0,0 +1,231 @@ +// SPDX-License-Identifier: GPL-3.0-or-later + +#ifndef NETDATA_PAGECACHE_H +#define NETDATA_PAGECACHE_H + +#include "rrdengine.h" + +/* Forward declarations */ +struct rrdengine_instance; +struct extent_info; +struct rrdeng_page_descr; + +#define INVALID_TIME (0) + +/* Page flags */ +#define RRD_PAGE_DIRTY (1LU << 0) +#define RRD_PAGE_LOCKED (1LU << 1) +#define RRD_PAGE_READ_PENDING (1LU << 2) +#define RRD_PAGE_WRITE_PENDING (1LU << 3) +#define RRD_PAGE_POPULATED (1LU << 4) + +struct page_cache_descr { + struct rrdeng_page_descr *descr; /* parent descriptor */ + void *page; + unsigned long flags; + struct page_cache_descr *prev; /* LRU */ + struct page_cache_descr *next; /* LRU */ + + unsigned refcnt; + uv_mutex_t mutex; /* always take it after the page cache lock or after the commit lock */ + uv_cond_t cond; + unsigned waiters; +}; + +/* Page cache descriptor flags, state = 0 means no descriptor */ +#define PG_CACHE_DESCR_ALLOCATED (1LU << 0) +#define PG_CACHE_DESCR_DESTROY (1LU << 1) +#define PG_CACHE_DESCR_LOCKED (1LU << 2) +#define PG_CACHE_DESCR_SHIFT (3) +#define PG_CACHE_DESCR_USERS_MASK (((unsigned long)-1) << PG_CACHE_DESCR_SHIFT) +#define PG_CACHE_DESCR_FLAGS_MASK (((unsigned long)-1) >> (BITS_PER_ULONG - PG_CACHE_DESCR_SHIFT)) + +/* + * Page cache descriptor state bits (works for both 32-bit and 64-bit architectures): + * + * 63 ... 31 ... 3 | 2 | 1 | 0| + * -----------------------------+------------+------------+-----------| + * number of descriptor users | DESTROY | LOCKED | ALLOCATED | + */ +struct rrdeng_page_descr { + uuid_t *id; /* never changes */ + struct extent_info *extent; + + /* points to ephemeral page cache descriptor if the page resides in the cache */ + struct page_cache_descr *pg_cache_descr; + + /* Compare-And-Swap target for page cache descriptor allocation algorithm */ + volatile unsigned long pg_cache_descr_state; + + /* page information */ + usec_t start_time; + usec_t end_time; + uint32_t page_length; +}; + +#define PAGE_INFO_SCRATCH_SZ (8) +struct rrdeng_page_info { + uint8_t scratch[PAGE_INFO_SCRATCH_SZ]; /* scratch area to be used by page-cache users */ + + usec_t start_time; + usec_t end_time; + uint32_t page_length; +}; + +/* returns 1 for success, 0 for failure */ +typedef int pg_cache_page_info_filter_t(struct rrdeng_page_descr *); + +#define PAGE_CACHE_MAX_PRELOAD_PAGES (256) + +/* maps time ranges to pages */ +struct pg_cache_page_index { + uuid_t id; + /* + * care: JudyL_array indices are converted from useconds to seconds to fit in one word in 32-bit architectures + * TODO: examine if we want to support better granularity than seconds + */ + Pvoid_t JudyL_array; + Word_t page_count; + unsigned short writers; + uv_rwlock_t lock; + + /* + * Only one effective writer, data deletion workqueue. + * It's also written during the DB loading phase. + */ + usec_t oldest_time; + + /* + * Only one effective writer, data collection thread. + * It's also written by the data deletion workqueue when data collection is disabled for this metric. + */ + usec_t latest_time; + + struct pg_cache_page_index *prev; +}; + +/* maps UUIDs to page indices */ +struct pg_cache_metrics_index { + uv_rwlock_t lock; + Pvoid_t JudyHS_array; + struct pg_cache_page_index *last_page_index; +}; + +/* gathers dirty pages to be written on disk */ +struct pg_cache_committed_page_index { + uv_rwlock_t lock; + + Pvoid_t JudyL_array; + + /* + * Dirty page correlation ID is a hint. Dirty pages that are correlated should have + * a small correlation ID difference. Dirty pages in memory should never have the + * same ID at the same time for correctness. + */ + Word_t latest_corr_id; + + unsigned nr_committed_pages; +}; + +/* + * Gathers populated pages to be evicted. + * Relies on page cache descriptors being there as it uses their memory. + */ +struct pg_cache_replaceQ { + uv_rwlock_t lock; /* LRU lock */ + + struct page_cache_descr *head; /* LRU */ + struct page_cache_descr *tail; /* MRU */ +}; + +struct page_cache { /* TODO: add statistics */ + uv_rwlock_t pg_cache_rwlock; /* page cache lock */ + + struct pg_cache_metrics_index metrics_index; + struct pg_cache_committed_page_index committed_page_index; + struct pg_cache_replaceQ replaceQ; + + unsigned page_descriptors; + unsigned populated_pages; +}; + +extern void pg_cache_wake_up_waiters_unsafe(struct rrdeng_page_descr *descr); +extern void pg_cache_wake_up_waiters(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr); +extern void pg_cache_wait_event_unsafe(struct rrdeng_page_descr *descr); +extern unsigned long pg_cache_wait_event(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr); +extern void pg_cache_replaceQ_insert(struct rrdengine_instance *ctx, + struct rrdeng_page_descr *descr); +extern void pg_cache_replaceQ_delete(struct rrdengine_instance *ctx, + struct rrdeng_page_descr *descr); +extern void pg_cache_replaceQ_set_hot(struct rrdengine_instance *ctx, + struct rrdeng_page_descr *descr); +extern struct rrdeng_page_descr *pg_cache_create_descr(void); +extern int pg_cache_try_get_unsafe(struct rrdeng_page_descr *descr, int exclusive_access); +extern void pg_cache_put_unsafe(struct rrdeng_page_descr *descr); +extern void pg_cache_put(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr); +extern void pg_cache_insert(struct rrdengine_instance *ctx, struct pg_cache_page_index *index, + struct rrdeng_page_descr *descr); +extern uint8_t pg_cache_punch_hole(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr, + uint8_t remove_dirty, uint8_t is_exclusive_holder, uuid_t *metric_id); +extern usec_t pg_cache_oldest_time_in_range(struct rrdengine_instance *ctx, uuid_t *id, + usec_t start_time, usec_t end_time); +extern void pg_cache_get_filtered_info_prev(struct rrdengine_instance *ctx, struct pg_cache_page_index *page_index, + usec_t point_in_time, pg_cache_page_info_filter_t *filter, + struct rrdeng_page_info *page_info); +extern unsigned + pg_cache_preload(struct rrdengine_instance *ctx, uuid_t *id, usec_t start_time, usec_t end_time, + struct rrdeng_page_info **page_info_arrayp, struct pg_cache_page_index **ret_page_indexp); +extern struct rrdeng_page_descr * + pg_cache_lookup(struct rrdengine_instance *ctx, struct pg_cache_page_index *index, uuid_t *id, + usec_t point_in_time); +extern struct rrdeng_page_descr * + pg_cache_lookup_next(struct rrdengine_instance *ctx, struct pg_cache_page_index *index, uuid_t *id, + usec_t start_time, usec_t end_time); +extern struct pg_cache_page_index *create_page_index(uuid_t *id); +extern void init_page_cache(struct rrdengine_instance *ctx); +extern void free_page_cache(struct rrdengine_instance *ctx); +extern void pg_cache_add_new_metric_time(struct pg_cache_page_index *page_index, struct rrdeng_page_descr *descr); +extern void pg_cache_update_metric_times(struct pg_cache_page_index *page_index); +extern unsigned long pg_cache_hard_limit(struct rrdengine_instance *ctx); +extern unsigned long pg_cache_soft_limit(struct rrdengine_instance *ctx); +extern unsigned long pg_cache_committed_hard_limit(struct rrdengine_instance *ctx); + +static inline void + pg_cache_atomic_get_pg_info(struct rrdeng_page_descr *descr, usec_t *end_timep, uint32_t *page_lengthp) +{ + usec_t end_time, old_end_time; + uint32_t page_length; + + if (NULL == descr->extent) { + /* this page is currently being modified, get consistent info locklessly */ + do { + end_time = descr->end_time; + __sync_synchronize(); + old_end_time = end_time; + page_length = descr->page_length; + __sync_synchronize(); + end_time = descr->end_time; + __sync_synchronize(); + } while ((end_time != old_end_time || (end_time & 1) != 0)); + + *end_timep = end_time; + *page_lengthp = page_length; + } else { + *end_timep = descr->end_time; + *page_lengthp = descr->page_length; + } +} + +/* The caller must hold a reference to the page and must have already set the new data */ +static inline void pg_cache_atomic_set_pg_info(struct rrdeng_page_descr *descr, usec_t end_time, uint32_t page_length) +{ + fatal_assert(!(end_time & 1)); + __sync_synchronize(); + descr->end_time |= 1; /* mark start of uncertainty period by adding 1 microsecond */ + __sync_synchronize(); + descr->page_length = page_length; + __sync_synchronize(); + descr->end_time = end_time; /* mark end of uncertainty period */ +} + +#endif /* NETDATA_PAGECACHE_H */ |