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// 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;
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_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 void pg_cache_punch_hole(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr, uint8_t remove_dirty);
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);
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)
{
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 */
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