src/lib-index/mail-cache-private.h

	mail-cache-private.h revision 9a583c7a827f7a4d89ee43774f2d51ea6a214543
#ifndef __MAIL_CACHE_PRIVATE_H
#define __MAIL_CACHE_PRIVATE_H

#include "file-dotlock.h"
#include "mail-index-private.h"
#include "mail-cache.h"

#define MAIL_CACHE_VERSION 1

/* Drop fields that haven't been accessed for n seconds */
#define MAIL_CACHE_FIELD_DROP_SECS (3600*24*30)

/* Never compress the file if it's smaller than this */
#define MAIL_CACHE_COMPRESS_MIN_SIZE (1024*50)

/* Don't bother remembering holes smaller than this */
#define MAIL_CACHE_MIN_HOLE_SIZE 1024

/* Compress the file when deleted space reaches n% of total size */
#define MAIL_CACHE_COMPRESS_PERCENTAGE 20

/* Compress the file when n% of rows contain continued rows.
   200% means that there's 2 continued rows per record. */
#define MAIL_CACHE_COMPRESS_CONTINUED_PERCENTAGE 200

/* Initial size for the file */
#define MAIL_CACHE_INITIAL_SIZE (sizeof(struct mail_cache_header) + 10240)

/* When more space is needed, grow the file n% larger than the previous size */
#define MAIL_CACHE_GROW_PERCENTAGE 10

/* When allocating space for transactions, don't use blocks larger than this. */
#define MAIL_CACHE_MAX_RESERVED_BLOCK_SIZE (1024*512)

#define MAIL_CACHE_LOCK_TIMEOUT 120
#define MAIL_CACHE_LOCK_CHANGE_TIMEOUT 60

#define CACHE_RECORD(cache, offset) \
    ((const struct mail_cache_record *) \
     ((const char *) (cache)->data + offset))

#define MAIL_CACHE_IS_UNUSABLE(cache) \
    ((cache)->hdr == NULL)

struct mail_cache_header {
    /* version is increased only when you can't have backwards
       compatibility. */
    uint8_t version;
    uint8_t compat_sizeof_uoff_t;
    uint8_t unused[2];

    uint32_t indexid;
    uint32_t file_seq;

    uint32_t continued_record_count;

    uint32_t hole_offset;
    uint32_t used_file_size;
    uint32_t deleted_space;

    uint32_t field_header_offset;
};

struct mail_cache_header_fields {
    uint32_t next_offset;
    uint32_t size;
    uint32_t fields_count;

#if 0
    /* last time the field was accessed. not updated more often than
       once a day. */
    uint32_t last_used[fields_count];
    /* (uint32_t)-1 for variable sized fields */
    uint32_t size[fields_count];
    /* enum mail_cache_field_type */
    uint8_t type[fields_count];
    /* enum mail_cache_decision_type */
    uint8_t decision[fields_count];
    /* NUL-separated list of field names */
    char name[fields_count][];
#endif
};

#define MAIL_CACHE_FIELD_LAST_USED() \
    (sizeof(uint32_t) * 3)
#define MAIL_CACHE_FIELD_SIZE(count) \
    (MAIL_CACHE_FIELD_LAST_USED() + sizeof(uint32_t) * (count))
#define MAIL_CACHE_FIELD_TYPE(count) \
    (MAIL_CACHE_FIELD_SIZE(count) + sizeof(uint32_t) * (count))
#define MAIL_CACHE_FIELD_DECISION(count) \
    (MAIL_CACHE_FIELD_TYPE(count) + sizeof(uint8_t) * (count))
#define MAIL_CACHE_FIELD_NAMES(count) \
    (MAIL_CACHE_FIELD_DECISION(count) + sizeof(uint8_t) * (count))

struct mail_cache_record {
    uint32_t prev_offset;
    uint32_t size; /* full record size, including this header */
    /* array of { uint32_t field; [ uint32_t size; ] { .. } } */
};

struct mail_cache_hole_header {
    uint32_t next_offset; /* 0 if no holes left */
    uint32_t size; /* including this header */

    /* make sure we notice if we're treating hole as mail_cache_record.
       magic is a large number so if it's treated as size field, it'll
       point outside the file */
#define MAIL_CACHE_HOLE_HEADER_MAGIC 0xffeedeff
    uint32_t magic;
};

struct mail_cache_field_private {
    struct mail_cache_field field;

    uint32_t uid_highwater;
    uint32_t last_used;

    /* Unused fields aren't written to cache file */
    unsigned int used:1;
    unsigned int decision_dirty:1;
};

struct mail_cache {
    struct mail_index *index;
    uint32_t ext_id;

    char *filepath;
    int fd;

    void *mmap_base;
    const void *data;
    size_t mmap_length;
    struct file_cache *file_cache;
    /* mail_cache_map() increases this always. */
    unsigned int remap_counter;

    struct dotlock_settings dotlock_settings;
    struct dotlock *dotlock;
    struct file_lock *file_lock;

    const struct mail_cache_header *hdr;
    struct mail_cache_header hdr_copy;

    pool_t field_pool;
    struct mail_cache_field_private *fields;
    uint32_t *field_file_map;
    unsigned int fields_count;
    struct hash_table *field_name_hash; /* name -> idx */

    /* 0 is no need for compression, otherwise the file sequence number
       which we want compressed. */
    uint32_t need_compress_file_seq;

    unsigned int *file_field_map;
    unsigned int file_fields_count;

    unsigned int opened:1;
    unsigned int locked:1;
    unsigned int hdr_modified:1;
    unsigned int field_header_write_pending:1;
};

struct mail_cache_view {
    struct mail_cache *cache;
    struct mail_index_view *view, *trans_view;

    struct mail_cache_transaction_ctx *transaction;
    uint32_t trans_seq1, trans_seq2;

    /* temporary array, just to avoid mallocs. */
    ARRAY_TYPE(uint32_t) looping_offsets;

    /* if cached_exists_buf[field] == cached_exists_value, it's cached.
       this allows us to avoid constantly clearing the whole buffer.
       it needs to be cleared only when cached_exists_value is wrapped. */
    buffer_t *cached_exists_buf;
    uint8_t cached_exists_value;
    uint32_t cached_exists_seq;
};

struct mail_cache_iterate_field {
    unsigned int field_idx;
    const void *data;
    unsigned int size;
};

struct mail_cache_lookup_iterate_ctx {
    struct mail_cache_view *view;
    unsigned int remap_counter;
    uint32_t seq;

    const struct mail_cache_record *rec;
    unsigned int pos, rec_size;
    uint32_t offset;

    unsigned int stop:1;
    unsigned int failed:1;
    unsigned int appends_checked:1;
};

int mail_cache_open_and_verify(struct mail_cache *cache);

/* Explicitly lock the cache file. Returns -1 if error, 1 if ok, 0 if we
   couldn't lock */
int mail_cache_lock(struct mail_cache *cache, bool require_same_reset_id);
/* Returns -1 if cache is / just got corrupted, 0 if ok. */
int mail_cache_unlock(struct mail_cache *cache);

void mail_cache_flush_read_cache(struct mail_cache *cache, bool just_locked);
int mail_cache_write(struct mail_cache *cache, const void *data, size_t size,
             uoff_t offset);

int mail_cache_header_fields_read(struct mail_cache *cache);
int mail_cache_header_fields_update(struct mail_cache *cache);
void mail_cache_header_fields_get(struct mail_cache *cache, buffer_t *dest);
int mail_cache_header_fields_get_next_offset(struct mail_cache *cache,
                         uint32_t *offset_r);

int mail_cache_get_record(struct mail_cache *cache, uint32_t offset,
              const struct mail_cache_record **rec_r);

/* Returns TRUE if offset is already in given array. Otherwise return FALSE
   and add the offset to the array. */
bool mail_cache_track_loops(ARRAY_TYPE(uint32_t) *array, uint32_t offset);

/* Iterate through a message's cached fields. */
void mail_cache_lookup_iter_init(struct mail_cache_view *view, uint32_t seq,
                 struct mail_cache_lookup_iterate_ctx *ctx_r);
/* Returns 1 if field was returned, 0 if end of fields, or -1 if error */
int mail_cache_lookup_iter_next(struct mail_cache_lookup_iterate_ctx *ctx,
                struct mail_cache_iterate_field *field_r);

int mail_cache_transaction_commit(struct mail_cache_transaction_ctx *ctx);
void mail_cache_transaction_rollback(struct mail_cache_transaction_ctx *ctx);

int mail_cache_map(struct mail_cache *cache, size_t offset, size_t size);
void mail_cache_file_close(struct mail_cache *cache);
int mail_cache_reopen(struct mail_cache *cache);

/* Update new_offset's prev_offset field to old_offset. */
int mail_cache_link(struct mail_cache *cache, uint32_t old_offset,
            uint32_t new_offset);
/* Mark record in given offset to be deleted. */
int mail_cache_delete(struct mail_cache *cache, uint32_t offset);

/* Notify the decision handling code that field was looked up for seq */
void mail_cache_decision_state_update(struct mail_cache_view *view,
                      uint32_t seq, unsigned int field);
void mail_cache_decision_add(struct mail_cache_view *view, uint32_t seq,
                 unsigned int field);

int mail_cache_expunge_handler(struct mail_index_sync_map_ctx *sync_ctx,
                   uint32_t seq, const void *data,
                   void **sync_context, void *context);
int mail_cache_sync_handler(struct mail_index_sync_map_ctx *sync_ctx,
                uint32_t seq, void *old_data, const void *new_data,
                void **context);
void mail_cache_sync_lost_handler(struct mail_index *index);

void mail_cache_set_syscall_error(struct mail_cache *cache,
                  const char *function);

#endif