1 files changed, 251 insertions, 0 deletions
diff --git a/src/database/engine/cache.h b/src/database/engine/cache.h
new file mode 100644
index 000000000..b6f81bcc2
--- /dev/null
+++ b/src/database/engine/cache.h
@@ -0,0 +1,251 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+#ifndef DBENGINE_CACHE_H
+#define DBENGINE_CACHE_H
+
+#include "datafile.h"
+#include "../rrd.h"
+
+// CACHE COMPILE TIME CONFIGURATION
+// #define PGC_COUNT_POINTS_COLLECTED 1
+
+typedef struct pgc PGC;
+typedef struct pgc_page PGC_PAGE;
+#define PGC_NAME_MAX 23
+
+typedef enum __attribute__ ((__packed__)) {
+    PGC_OPTIONS_NONE       = 0,
+    PGC_OPTIONS_EVICT_PAGES_INLINE = (1 << 0),
+    PGC_OPTIONS_FLUSH_PAGES_INLINE = (1 << 1),
+    PGC_OPTIONS_AUTOSCALE          = (1 << 2),
+} PGC_OPTIONS;
+
+#define PGC_OPTIONS_DEFAULT (PGC_OPTIONS_EVICT_PAGES_INLINE | PGC_OPTIONS_FLUSH_PAGES_INLINE | PGC_OPTIONS_AUTOSCALE)
+
+typedef struct pgc_entry {
+    Word_t section;             // the section this belongs to
+    Word_t metric_id;           // the metric this belongs to
+    time_t start_time_s;        // the start time of the page
+    time_t end_time_s;          // the end time of the page
+    size_t size;                // the size in bytes of the allocation, outside the cache
+    void *data;                 // a pointer to data outside the cache
+    uint32_t update_every_s;    // the update every of the page
+    bool hot;                   // true if this entry is currently being collected
+    uint8_t *custom_data;
+} PGC_ENTRY;
+
+#define PGC_CACHE_LINE_PADDING(x) uint8_t padding##x[64]
+
+struct pgc_queue_statistics {
+    size_t entries;
+    size_t size;
+
+    PGC_CACHE_LINE_PADDING(1);
+
+    size_t max_entries;
+    size_t max_size;
+
+    PGC_CACHE_LINE_PADDING(2);
+
+    size_t added_entries;
+    size_t added_size;
+
+    PGC_CACHE_LINE_PADDING(3);
+
+    size_t removed_entries;
+    size_t removed_size;
+
+    PGC_CACHE_LINE_PADDING(4);
+};
+
+struct pgc_statistics {
+    size_t wanted_cache_size;
+    size_t current_cache_size;
+
+    PGC_CACHE_LINE_PADDING(1);
+
+    size_t added_entries;
+    size_t added_size;
+
+    PGC_CACHE_LINE_PADDING(2);
+
+    size_t removed_entries;
+    size_t removed_size;
+
+    PGC_CACHE_LINE_PADDING(3);
+
+    size_t entries;                 // all the entries (includes clean, dirty, hot)
+    size_t size;                    // all the entries (includes clean, dirty, hot)
+
+    size_t evicting_entries;
+    size_t evicting_size;
+
+    size_t flushing_entries;
+    size_t flushing_size;
+
+    size_t hot2dirty_entries;
+    size_t hot2dirty_size;
+
+    PGC_CACHE_LINE_PADDING(4);
+
+    size_t acquires;
+    PGC_CACHE_LINE_PADDING(4a);
+    size_t releases;
+    PGC_CACHE_LINE_PADDING(4b);
+    size_t acquires_for_deletion;
+    PGC_CACHE_LINE_PADDING(4c);
+
+    size_t referenced_entries;      // all the entries currently referenced
+    size_t referenced_size;         // all the entries currently referenced
+
+    PGC_CACHE_LINE_PADDING(5);
+
+    size_t searches_exact;
+    size_t searches_exact_hits;
+    size_t searches_exact_misses;
+
+    PGC_CACHE_LINE_PADDING(6);
+
+    size_t searches_closest;
+    size_t searches_closest_hits;
+    size_t searches_closest_misses;
+
+    PGC_CACHE_LINE_PADDING(7);
+
+    size_t flushes_completed;
+    size_t flushes_completed_size;
+    size_t flushes_cancelled;
+    size_t flushes_cancelled_size;
+
+#ifdef PGC_COUNT_POINTS_COLLECTED
+    PGC_CACHE_LINE_PADDING(8);
+    size_t points_collected;
+#endif
+
+    PGC_CACHE_LINE_PADDING(9);
+
+    size_t insert_spins;
+    size_t evict_spins;
+    size_t release_spins;
+    size_t acquire_spins;
+    size_t delete_spins;
+    size_t flush_spins;
+
+    PGC_CACHE_LINE_PADDING(10);
+
+    size_t workers_search;
+    size_t workers_add;
+    size_t workers_evict;
+    size_t workers_flush;
+    size_t workers_jv2_flush;
+    size_t workers_hot2dirty;
+
+    size_t evict_skipped;
+    size_t hot_empty_pages_evicted_immediately;
+    size_t hot_empty_pages_evicted_later;
+
+    PGC_CACHE_LINE_PADDING(11);
+
+    // events
+    size_t events_cache_under_severe_pressure;
+    size_t events_cache_needs_space_aggressively;
+    size_t events_flush_critical;
+
+    PGC_CACHE_LINE_PADDING(12);
+
+    struct {
+        PGC_CACHE_LINE_PADDING(0);
+        struct pgc_queue_statistics hot;
+        PGC_CACHE_LINE_PADDING(1);
+        struct pgc_queue_statistics dirty;
+        PGC_CACHE_LINE_PADDING(2);
+        struct pgc_queue_statistics clean;
+        PGC_CACHE_LINE_PADDING(3);
+    } queues;
+};
+
+
+typedef void (*free_clean_page_callback)(PGC *cache, PGC_ENTRY entry);
+typedef void (*save_dirty_page_callback)(PGC *cache, PGC_ENTRY *entries_array, PGC_PAGE **pages_array, size_t entries);
+typedef void (*save_dirty_init_callback)(PGC *cache, Word_t section);
+// create a cache
+PGC *pgc_create(const char *name,
+                size_t clean_size_bytes, free_clean_page_callback pgc_free_clean_cb,
+                size_t max_dirty_pages_per_flush, save_dirty_init_callback pgc_save_init_cb, save_dirty_page_callback pgc_save_dirty_cb,
+                size_t max_pages_per_inline_eviction, size_t max_inline_evictors,
+                size_t max_skip_pages_per_inline_eviction,
+                size_t max_flushes_inline,
+                PGC_OPTIONS options, size_t partitions, size_t additional_bytes_per_page);
+
+// destroy the cache
+void pgc_destroy(PGC *cache);
+
+#define PGC_SECTION_ALL ((Word_t)0)
+void pgc_flush_all_hot_and_dirty_pages(PGC *cache, Word_t section);
+
+// add a page to the cache and return a pointer to it
+PGC_PAGE *pgc_page_add_and_acquire(PGC *cache, PGC_ENTRY entry, bool *added);
+
+// get another reference counter on an already referenced page
+PGC_PAGE *pgc_page_dup(PGC *cache, PGC_PAGE *page);
+
+// release a page (all pointers to it are now invalid)
+void pgc_page_release(PGC *cache, PGC_PAGE *page);
+
+// mark a hot page dirty, and release it
+void pgc_page_hot_to_dirty_and_release(PGC *cache, PGC_PAGE *page, bool never_flush);
+
+// find a page from the cache
+typedef enum {
+    PGC_SEARCH_EXACT,
+    PGC_SEARCH_CLOSEST,
+    PGC_SEARCH_FIRST,
+    PGC_SEARCH_NEXT,
+    PGC_SEARCH_LAST,
+    PGC_SEARCH_PREV,
+} PGC_SEARCH;
+
+PGC_PAGE *pgc_page_get_and_acquire(PGC *cache, Word_t section, Word_t metric_id, time_t start_time_s, PGC_SEARCH method);
+
+// get information from an acquired page
+Word_t pgc_page_section(PGC_PAGE *page);
+Word_t pgc_page_metric(PGC_PAGE *page);
+time_t pgc_page_start_time_s(PGC_PAGE *page);
+time_t pgc_page_end_time_s(PGC_PAGE *page);
+uint32_t pgc_page_update_every_s(PGC_PAGE *page);
+uint32_t pgc_page_fix_update_every(PGC_PAGE *page, uint32_t update_every_s);
+time_t pgc_page_fix_end_time_s(PGC_PAGE *page, time_t end_time_s);
+void *pgc_page_data(PGC_PAGE *page);
+void *pgc_page_custom_data(PGC *cache, PGC_PAGE *page);
+size_t pgc_page_data_size(PGC *cache, PGC_PAGE *page);
+bool pgc_is_page_hot(PGC_PAGE *page);
+bool pgc_is_page_dirty(PGC_PAGE *page);
+bool pgc_is_page_clean(PGC_PAGE *page);
+void pgc_reset_hot_max(PGC *cache);
+size_t pgc_get_current_cache_size(PGC *cache);
+size_t pgc_get_wanted_cache_size(PGC *cache);
+
+// resetting the end time of a hot page
+void pgc_page_hot_set_end_time_s(PGC *cache, PGC_PAGE *page, time_t end_time_s);
+bool pgc_page_to_clean_evict_or_release(PGC *cache, PGC_PAGE *page);
+
+typedef void (*migrate_to_v2_callback)(Word_t section, unsigned datafile_fileno, uint8_t type, Pvoid_t JudyL_metrics, Pvoid_t JudyL_extents_pos, size_t count_of_unique_extents, size_t count_of_unique_metrics, size_t count_of_unique_pages, void *data);
+void pgc_open_cache_to_journal_v2(PGC *cache, Word_t section, unsigned datafile_fileno, uint8_t type, migrate_to_v2_callback cb, void *data);
+void pgc_open_evict_clean_pages_of_datafile(PGC *cache, struct rrdengine_datafile *datafile);
+size_t pgc_count_clean_pages_having_data_ptr(PGC *cache, Word_t section, void *ptr);
+size_t pgc_count_hot_pages_having_data_ptr(PGC *cache, Word_t section, void *ptr);
+
+typedef size_t (*dynamic_target_cache_size_callback)(void);
+void pgc_set_dynamic_target_cache_size_callback(PGC *cache, dynamic_target_cache_size_callback callback);
+
+// return true when there is more work to do
+bool pgc_evict_pages(PGC *cache, size_t max_skip, size_t max_evict);
+bool pgc_flush_pages(PGC *cache, size_t max_flushes);
+
+struct pgc_statistics pgc_get_statistics(PGC *cache);
+size_t pgc_hot_and_dirty_entries(PGC *cache);
+
+struct aral_statistics *pgc_aral_statistics(void);
+size_t pgc_aral_structures(void);
+size_t pgc_aral_overhead(void);
+
+#endif // DBENGINE_CACHE_H