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-rw-r--r--database/engine/pagecache.h231
1 files changed, 231 insertions, 0 deletions
diff --git a/database/engine/pagecache.h b/database/engine/pagecache.h
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--- /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 */