src/lib-index/mail-cache-sync-update.c

	mail-cache-sync-update.c revision b14bdce468df7d98afb3e5e8c71b74a75cad2453
/* Copyright (c) 2004-2012 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "buffer.h"
#include "file-cache.h"
#include "mail-cache-private.h"
#include "mail-index-view-private.h"
#include "mail-index-sync-private.h"

struct mail_cache_sync_context {
    uoff_t invalidate_highwater;

    unsigned int locked:1;
    unsigned int lock_failed:1;
    unsigned int nfs_read_cache_flushed:1;
};

static void mail_cache_handler_deinit(struct mail_index_sync_map_ctx *sync_ctx,
                      struct mail_cache_sync_context *ctx)
{
    if (ctx == NULL)
        return;

    if (ctx->locked)
        (void)mail_cache_unlock(sync_ctx->view->index->cache);
    i_free(ctx);
}

static struct mail_cache_sync_context *mail_cache_handler_init(void **context)
{
    struct mail_cache_sync_context *ctx;

    if (*context != NULL)
        ctx = *context;
    else {
        *context = i_new(struct mail_cache_sync_context, 1);
        ctx = *context;
        ctx->invalidate_highwater = (uoff_t)-1;
    }
    return ctx;
}

static int mail_cache_handler_lock(struct mail_cache_sync_context *ctx,
                   struct mail_cache *cache)
{
    int ret;

    if (ctx->locked)
        return MAIL_CACHE_IS_UNUSABLE(cache) ? 0 : 1;
    if (ctx->lock_failed)
        return 0;

    if (!ctx->locked) {
        if ((ret = mail_cache_lock(cache, TRUE)) <= 0) {
                        ctx->lock_failed = TRUE;
            return ret;
        }
        ctx->locked = TRUE;
    }
    return 1;
}

static bool get_cache_file_seq(struct mail_index_view *view,
                  uint32_t *cache_file_seq_r)
{
    const struct mail_index_ext *ext;

    ext = mail_index_view_get_ext(view, view->index->cache->ext_id);
    if (ext == NULL)
        return FALSE;

    *cache_file_seq_r = ext->reset_id;
    return TRUE;
}

int mail_cache_expunge_handler(struct mail_index_sync_map_ctx *sync_ctx,
                   uint32_t seq ATTR_UNUSED, const void *data,
                   void **sync_context, void *context)
{
    struct mail_cache *cache = context;
    struct mail_cache_sync_context *ctx = *sync_context;
    const uint32_t *cache_offset = data;
    uint32_t cache_file_seq;
    int ret;

    if (data == NULL) {
        mail_cache_handler_deinit(sync_ctx, ctx);
        *sync_context = NULL;
        return 0;
    }

    if (*cache_offset == 0)
        return 0;

    ctx = mail_cache_handler_init(sync_context);
    ret = mail_cache_handler_lock(ctx, cache);
    if (ret <= 0)
        return ret;

    if (!get_cache_file_seq(sync_ctx->view, &cache_file_seq))
        return 0;

    if (!MAIL_CACHE_IS_UNUSABLE(cache) &&
        cache_file_seq == cache->hdr->file_seq)
        (void)mail_cache_delete(cache, *cache_offset);
    return 0;
}

int mail_cache_sync_handler(struct mail_index_sync_map_ctx *sync_ctx,
                uint32_t seq ATTR_UNUSED,
                void *old_data, const void *new_data,
                void **context)
{
    struct mail_index_view *view = sync_ctx->view;
    struct mail_index *index = view->index;
    struct mail_cache *cache = index->cache;
    struct mail_cache_sync_context *ctx = *context;
    const uint32_t *old_cache_offset = old_data;
    const uint32_t *new_cache_offset = new_data;
    uint32_t cache_file_seq, cur_seq, tail_seq;
    uoff_t cur_offset, tail_offset;
    int ret;

    if (new_cache_offset == NULL) {
        mail_cache_handler_deinit(sync_ctx, ctx);
        *context = NULL;
        return 1;
    }

    ctx = mail_cache_handler_init(context);
    if (cache->file_cache != NULL && !MAIL_CACHE_IS_UNUSABLE(cache)) {
        /* flush read cache only once per sync */
        if (!ctx->nfs_read_cache_flushed &&
            (index->flags & MAIL_INDEX_OPEN_FLAG_NFS_FLUSH) != 0) {
            ctx->nfs_read_cache_flushed = TRUE;
            mail_index_flush_read_cache(index,
                            cache->filepath, cache->fd,
                            cache->locked);
        }
        /* don't invalidate anything that's already been invalidated
           within this sync. */
        if (*new_cache_offset < ctx->invalidate_highwater) {
            file_cache_invalidate(cache->file_cache,
                          *new_cache_offset,
                          ctx->invalidate_highwater -
                          *new_cache_offset);
            ctx->invalidate_highwater = *new_cache_offset;
            if (cache->read_buf != NULL)
                buffer_set_used_size(cache->read_buf, 0);
        }
    }

    if (*old_cache_offset == 0 || *old_cache_offset == *new_cache_offset ||
        sync_ctx->type == MAIL_INDEX_SYNC_HANDLER_VIEW)
        return 1;

    mail_transaction_log_view_get_prev_pos(view->log_view,
                           &cur_seq, &cur_offset);
    mail_transaction_log_get_mailbox_sync_pos(index->log,
                          &tail_seq, &tail_offset);
    if (LOG_IS_BEFORE(cur_seq, cur_offset, tail_seq, tail_offset)) {
        /* already been linked */
        return 1;
    }

    /* we'll need to link the old and new cache records */
    ret = mail_cache_handler_lock(ctx, cache);
    if (ret <= 0)
        return ret < 0 ? -1 : 1;

    if (!get_cache_file_seq(view, &cache_file_seq))
        return 1;

    if (cache_file_seq != cache->hdr->file_seq) {
        /* cache has been compressed, don't modify it */
        return 1;
    }

    if (mail_cache_link(cache, *old_cache_offset, *new_cache_offset) < 0)
        return -1;

    return 1;
}

void mail_cache_sync_lost_handler(struct mail_index *index)
{
    struct mail_cache *cache = index->cache;

    if (!MAIL_CACHE_IS_UNUSABLE(cache)) {
        mail_index_flush_read_cache(cache->index, cache->filepath,
                        cache->fd, cache->locked);
    }
    file_cache_invalidate(cache->file_cache, 0, (uoff_t)-1);
    if (cache->read_buf != NULL)
        buffer_set_used_size(cache->read_buf, 0);
}