src/lib-index/mail-cache.c

	mail-cache.c revision 5626ae5e3316eced244adb6485c0927f1c7fdc41
/* Copyright (C) 2003-2004 Timo Sirainen */

#include "lib.h"
#include "buffer.h"
#include "hash.h"
#include "file-cache.h"
#include "mmap-util.h"
#include "write-full.h"
#include "mail-cache-private.h"

#include <unistd.h>

void mail_cache_set_syscall_error(struct mail_cache *cache,
                  const char *function)
{
    i_assert(function != NULL);

    if (ENOSPACE(errno)) {
        cache->index->nodiskspace = TRUE;
        return;
    }

    mail_index_set_error(cache->index,
                 "%s failed with index cache file %s: %m",
                 function, cache->filepath);
}

void mail_cache_set_corrupted(struct mail_cache *cache, const char *fmt, ...)
{
    va_list va;

    (void)unlink(cache->filepath);
    mail_cache_file_close(cache);

    va_start(va, fmt);
    t_push();
    mail_index_set_error(cache->index, "Corrupted index cache file %s: %s",
                 cache->filepath, t_strdup_vprintf(fmt, va));
    t_pop();
    va_end(va);
}

void mail_cache_file_close(struct mail_cache *cache)
{
    if (cache->mmap_base != NULL) {
        if (munmap(cache->mmap_base, cache->mmap_length) < 0)
            mail_cache_set_syscall_error(cache, "munmap()");
    }

    if (cache->file_cache != NULL)
        file_cache_set_fd(cache->file_cache, -1);

    cache->mmap_base = NULL;
    cache->data = NULL;
    cache->hdr = NULL;
    cache->mmap_length = 0;

    if (cache->fd != -1) {
        if (close(cache->fd) < 0)
            mail_cache_set_syscall_error(cache, "close()");
        cache->fd = -1;
    }
}

int mail_cache_reopen(struct mail_cache *cache)
{
    struct mail_index_view *view;
    const struct mail_index_ext *ext;

    if (MAIL_CACHE_IS_UNUSABLE(cache) && cache->need_compress) {
        /* unusable, we're just waiting for compression */
        return 0;
    }

    mail_cache_file_close(cache);

    cache->fd = open(cache->filepath, O_RDWR);
    if (cache->fd == -1) {
        if (errno == ENOENT)
            cache->need_compress = TRUE;
        else
            mail_cache_set_syscall_error(cache, "open()");
        return -1;
    }

    if (cache->file_cache != NULL)
        file_cache_set_fd(cache->file_cache, cache->fd);

    if (mail_cache_map(cache, 0, 0) < 0)
        return -1;

    if (mail_cache_header_fields_read(cache) < 0)
        return -1;

    view = mail_index_view_open(cache->index);
    ext = mail_index_view_get_ext(view, cache->ext_id);
    if (ext == NULL || cache->hdr->file_seq != ext->reset_id) {
        /* still different - maybe a race condition or maybe the
           file_seq really is corrupted. either way, this shouldn't
           happen often so we'll just mark cache to be compressed
           later which fixes this. */
        cache->need_compress = TRUE;
        mail_index_view_close(view);
        return 0;
    }

    mail_index_view_close(view);
    return 1;
}

static int mail_cache_verify_header(struct mail_cache *cache)
{
    const struct mail_cache_header *hdr = cache->data;

    /* check that the header is still ok */
    if (cache->mmap_length < sizeof(struct mail_cache_header)) {
        mail_cache_set_corrupted(cache, "File too small");
        return FALSE;
    }

    if (cache->hdr->version != MAIL_CACHE_VERSION) {
        /* version changed - upgrade silently */
        return FALSE;
    }

    if (cache->hdr->indexid != cache->index->indexid) {
        /* index id changed */
        mail_cache_set_corrupted(cache, "indexid changed");
        return FALSE;
    }

    /* only check the header if we're locked */
    if (!cache->locked)
        return TRUE;

    if (hdr->used_file_size < sizeof(struct mail_cache_header)) {
        mail_cache_set_corrupted(cache, "used_file_size too small");
        return FALSE;
    }
    if ((hdr->used_file_size % sizeof(uint32_t)) != 0) {
        mail_cache_set_corrupted(cache, "used_file_size not aligned");
        return FALSE;
    }

    if (cache->mmap_base != NULL &&
        hdr->used_file_size > cache->mmap_length) {
        mail_cache_set_corrupted(cache, "used_file_size too large");
        return FALSE;
    }
    return TRUE;
}

int mail_cache_map(struct mail_cache *cache, size_t offset, size_t size)
{
    ssize_t ret;

    if (size == 0)
        size = sizeof(struct mail_cache_header);

    if (cache->file_cache != NULL) {
        cache->data = NULL;
        cache->hdr = NULL;

        ret = file_cache_read(cache->file_cache, offset, size);
        if (ret < 0) {
            // FIXME: ESTALE
            mail_cache_set_syscall_error(cache, "read()");
            return -1;
        }

        cache->data = file_cache_get_map(cache->file_cache,
                         &cache->mmap_length);
        cache->hdr = cache->data;

        if (offset == 0 && !mail_cache_verify_header(cache)) {
            cache->need_compress = TRUE;
            return -1;
        }
        return 0;
    }

    if (offset < cache->mmap_length &&
        size <= cache->mmap_length - offset) {
        /* already mapped */
        return 0;
    }

    if (cache->mmap_base != NULL) {
        if (munmap(cache->mmap_base, cache->mmap_length) < 0)
            mail_cache_set_syscall_error(cache, "munmap()");
    } else {
        if (cache->fd == -1) {
            /* unusable, waiting for compression */
            i_assert(cache->need_compress);
            return -1;
        }
    }

    /* map the whole file */
    cache->hdr = NULL;
    cache->mmap_length = 0;

    cache->mmap_base = mmap_ro_file(cache->fd, &cache->mmap_length);
    if (cache->mmap_base == MAP_FAILED) {
        cache->mmap_base = NULL;
        cache->data = NULL;
        mail_cache_set_syscall_error(cache, "mmap()");
        return -1;
    }
    cache->data = cache->mmap_base;
    cache->hdr = cache->mmap_base;

    if (!mail_cache_verify_header(cache)) {
        cache->need_compress = TRUE;
        return -1;
    }

    return 0;
}

static int mail_cache_open_and_verify(struct mail_cache *cache)
{
    cache->filepath = i_strconcat(cache->index->filepath,
                      MAIL_CACHE_FILE_PREFIX, NULL);

    if (cache->index->mmap_disable || cache->index->mmap_no_write)
        cache->file_cache = file_cache_new(-1);

    cache->fd = open(cache->filepath, O_RDWR);
    if (cache->fd == -1) {
        if (errno == ENOENT) {
            cache->need_compress = TRUE;
            return 0;
        }

        mail_cache_set_syscall_error(cache, "open()");
        return -1;
    }

    if (cache->file_cache != NULL)
        file_cache_set_fd(cache->file_cache, cache->fd);

    if (mail_cache_map(cache, 0, sizeof(struct mail_cache_header)) < 0)
        return -1;

    return mail_cache_header_fields_read(cache);
}

struct mail_cache *mail_cache_open_or_create(struct mail_index *index)
{
    struct mail_cache *cache;

    cache = i_new(struct mail_cache, 1);
    cache->index = index;
    cache->fd = -1;
        cache->field_pool = pool_alloconly_create("Cache fields", 1024);
    cache->field_name_hash =
        hash_create(default_pool, cache->field_pool, 0,
                strcase_hash, (hash_cmp_callback_t *)strcasecmp);

    if (mail_cache_open_and_verify(cache) < 0) {
        /* failed for some reason - doesn't really matter,
           it's disabled for now. */
        mail_cache_file_close(cache);
    }

    cache->ext_id =
        mail_index_ext_register(index, "cache", 0,
                    sizeof(uint32_t), sizeof(uint32_t));
    mail_index_register_expunge_handler(index, cache->ext_id,
                        mail_cache_expunge_handler);
    mail_index_register_sync_handler(index, cache->ext_id,
                     mail_cache_sync_handler,
                     cache->file_cache != NULL);
    return cache;
}

void mail_cache_free(struct mail_cache *cache)
{
    if (cache->file_cache != NULL) {
        file_cache_free(cache->file_cache);
        cache->file_cache = NULL;
    }

    mail_cache_file_close(cache);

    hash_destroy(cache->field_name_hash);
    pool_unref(cache->field_pool);
    i_free(cache->field_file_map);
    i_free(cache->file_field_map);
    i_free(cache->fields);
    i_free(cache->filepath);
    i_free(cache);
}

int mail_cache_lock(struct mail_cache *cache)
{
    struct mail_index_view *view;
    const struct mail_index_ext *ext;
    int i, ret;

    i_assert(!cache->locked);

    if (MAIL_CACHE_IS_UNUSABLE(cache))
        return 0;

    if (mail_index_view_open_locked(cache->index, &view) < 0)
        return -1;

    ext = mail_index_view_get_ext(view, cache->ext_id);
    if (ext == NULL) {
        /* cache not used */
        mail_index_view_close(view);
        return 0;
    }

    if (cache->hdr->file_seq != ext->reset_id) {
        /* we want the latest cache file */
        if ((ret = mail_cache_reopen(cache)) <= 0) {
            mail_index_view_close(view);
            return ret;
        }
    }

    for (i = 0; i < 3; i++) {
        ret = mail_index_lock_fd(cache->index, cache->fd, F_WRLCK,
                     MAIL_INDEX_LOCK_SECS);
        if (ret <= 0) {
            mail_cache_set_syscall_error(cache,
                "mail_index_wait_lock_fd()");
            break;
        }
        cache->locked = TRUE;

        if (cache->hdr->file_seq == ext->reset_id) {
            /* got it */
            break;
        }

        /* okay, so it was just compressed. try again. */
        mail_cache_unlock(cache);
        if ((ret = mail_cache_reopen(cache)) <= 0)
            break;
        ret = 0;
    }

    if (ret > 0) {
        /* make sure our header is up to date */
        if (cache->file_cache != NULL) {
            file_cache_invalidate(cache->file_cache, 0,
                          sizeof(struct mail_cache_header));
        }
        if (mail_cache_map(cache, 0, 0) < 0)
            ret = -1;
        cache->hdr_copy = *cache->hdr;
    }

    mail_index_view_close(view);
    return ret;
}

static void mail_cache_update_need_compress(struct mail_cache *cache)
{
    const struct mail_cache_header *hdr = cache->hdr;
    unsigned int cont_percentage;
    uoff_t max_del_space;

        cont_percentage = hdr->continued_record_count * 100 /
        (cache->index->map->records_count == 0 ? 1 :
         cache->index->map->records_count);
    if (cont_percentage >= COMPRESS_CONTINUED_PERCENTAGE &&
        hdr->used_file_size >= COMPRESS_MIN_SIZE) {
        /* too many continued rows, compress */
        cache->need_compress = TRUE;
    }

    /* see if we've reached the max. deleted space in file */
    max_del_space = hdr->used_file_size / 100 * COMPRESS_PERCENTAGE;
    if (hdr->deleted_space >= max_del_space &&
        hdr->used_file_size >= COMPRESS_MIN_SIZE)
        cache->need_compress = TRUE;
}

void mail_cache_unlock(struct mail_cache *cache)
{
    i_assert(cache->locked);

    if (cache->field_header_write_pending)
                (void)mail_cache_header_fields_update(cache);

    cache->locked = FALSE;

    if (cache->hdr_modified) {
        cache->hdr_modified = FALSE;
        if (pwrite_full(cache->fd, &cache->hdr_copy,
                sizeof(cache->hdr_copy), 0) < 0)
            mail_cache_set_syscall_error(cache, "pwrite_full()");
        mail_cache_update_need_compress(cache);
    }

    if (mail_index_lock_fd(cache->index, cache->fd, F_UNLCK, 0) <= 0) {
        mail_cache_set_syscall_error(cache,
            "mail_index_wait_lock_fd(F_UNLCK)");
    }
}

struct mail_cache_view *
mail_cache_view_open(struct mail_cache *cache, struct mail_index_view *iview)
{
    struct mail_cache_view *view;

    view = i_new(struct mail_cache_view, 1);
    view->cache = cache;
    view->view = iview;
    view->offsets_buf = buffer_create_dynamic(default_pool, 128);
    view->cached_exists_buf =
        buffer_create_dynamic(default_pool,
                      cache->file_fields_count + 10);
    return view;
}

void mail_cache_view_close(struct mail_cache_view *view)
{
    if (view->cache->field_header_write_pending)
                (void)mail_cache_header_fields_update(view->cache);

    if (view->trans_view != NULL)
        mail_index_view_close(view->trans_view);

    buffer_free(view->offsets_buf);
    buffer_free(view->cached_exists_buf);
    i_free(view);
}