src/lib-index/mail-index-view-sync.c

	mail-index-view-sync.c revision 51795bfe9d05d92fe942cb451aec2b9d16d32a11
2ronwalf/* Copyright (C) 2003-2004 Timo Sirainen */
2ronwalf
2ronwalf#include "lib.h"
22daenzerorama#include "array.h"
2ronwalf#include "buffer.h"
2ronwalf#include "mail-index-view-private.h"
2ronwalf#include "mail-index-sync-private.h"
2ronwalf#include "mail-transaction-log.h"
2ronwalf
2ronwalfstruct mail_index_view_sync_ctx {
2ronwalf    struct mail_index_view *view;
2ronwalf    enum mail_transaction_type visible_sync_mask;
2ronwalf    struct mail_index_sync_map_ctx sync_map_ctx;
2ronwalf    ARRAY_TYPE(seq_range) expunges;
2ronwalf
2ronwalf    const struct mail_transaction_header *hdr;
2ronwalf    const void *data;
2ronwalf
2ronwalf    size_t data_offset;
2ronwalf    unsigned int sync_map_update:1;
2ronwalf    unsigned int skipped_appends:1;
2ronwalf    unsigned int skipped_expunges:1;
2ronwalf    unsigned int last_read:1;
2ronwalf};
2ronwalf
2ronwalfstatic int
2ronwalfmail_transaction_log_sort_expunges(ARRAY_TYPE(seq_range) *expunges,
2ronwalf                   const struct seq_range *src, size_t src_size)
2ronwalf{
2ronwalf    /* Note that all the sequences are actually still UIDs at this point */
2ronwalf    const struct seq_range *src_end;
2ronwalf    struct seq_range *dest, new_exp;
2ronwalf    unsigned int first, i, dest_count;
2ronwalf
2ronwalf    i_assert(src_size % sizeof(*src) == 0);
2ronwalf
2ronwalf    /* @UNSAFE */
2ronwalf    dest = array_get_modifiable(expunges, &dest_count);
2ronwalf    if (dest_count == 0) {
2ronwalf        array_append(expunges, src, src_size / sizeof(*src));
        return 0;
    }

    src_end = CONST_PTR_OFFSET(src, src_size);
    for (i = 0; src != src_end; src++) {
        /* src[] must be sorted. */
        if (src->seq1 > src->seq2 ||
            (src+1 != src_end && src->seq2 >= src[1].seq1))
            return -1;

        for (; i < dest_count; i++) {
            if (src->seq1 < dest[i].seq1)
                break;
        }

        new_exp = *src;

        first = i;
        while (i < dest_count && src->seq2 >= dest[i].seq1-1) {
            /* we can/must merge with next record */
            if (new_exp.seq2 < dest[i].seq2)
                new_exp.seq2 = dest[i].seq2;
            i++;
        }

        if (first > 0 && new_exp.seq1 <= dest[first-1].seq2+1) {
            /* continue previous record */
            if (dest[first-1].seq2 < new_exp.seq2)
                dest[first-1].seq2 = new_exp.seq2;
        } else if (i == first) {
            array_insert(expunges, i, &new_exp, 1);
            i++; first++;

            dest = array_get_modifiable(expunges, &dest_count);
        } else {
            /* use next record */
            dest[first] = new_exp;
            first++;
        }

        if (i > first) {
            array_delete(expunges, first, i - first);

            dest = array_get_modifiable(expunges, &dest_count);
            i = first;
        }
    }
    return 0;
}

static void view_sync_get_tail(struct mail_index_view *view,
                   uint32_t *seq_r, uoff_t *offset_r)
{
    if (LOG_IS_BEFORE(view->log_file_append_seq,
              view->log_file_append_offset,
              view->log_file_expunge_seq,
              view->log_file_expunge_offset)) {
        *seq_r = view->log_file_append_seq;
        *offset_r = view->log_file_append_offset;
    } else {
        *seq_r = view->log_file_expunge_seq;
        *offset_r = view->log_file_expunge_offset;
    }
    i_assert(!LOG_IS_BEFORE(view->log_file_head_seq,
                view->log_file_head_offset,
                *seq_r, *offset_r));
}

static int view_sync_set_log_view_range(struct mail_index_view *view)
{
    const struct mail_index_header *hdr = view->index->hdr;
    uint32_t tail_seq;
    uoff_t tail_offset;
    int ret;

    view_sync_get_tail(view, &tail_seq, &tail_offset);

    /* the view begins from the first non-synced transaction */
    ret = mail_transaction_log_view_set(view->log_view,
                        tail_seq, tail_offset,
                        hdr->log_file_seq,
                        hdr->log_file_head_offset);
    if (ret <= 0) {
        if (ret == 0) {
            /* FIXME: use the new index to get needed changes */
            mail_index_set_error(view->index,
                "Transaction log got desynced for index %s",
                view->index->filepath);
            mail_index_set_inconsistent(view->index);
        }
        return -1;
    }
    return 0;
}

static int
view_sync_get_expunges(struct mail_index_view *view,
               ARRAY_TYPE(seq_range) *expunges_r)
{
    const struct mail_transaction_header *hdr;
    struct seq_range *src, *src_end, *dest;
    const void *data;
    unsigned int count;
    int ret;

    if (view_sync_set_log_view_range(view) < 0)
        return -1;

    /* get a list of expunge transactions. there may be some that we have
       already synced, but it doesn't matter because they'll get dropped
       out when converting to sequences */
    i_array_init(expunges_r, 64);
    while ((ret = mail_transaction_log_view_next(view->log_view,
                             &hdr, &data)) > 0) {
        if ((hdr->type & MAIL_TRANSACTION_EXPUNGE) == 0)
            continue;
        if ((hdr->type & MAIL_TRANSACTION_EXTERNAL) == 0) {
            /* this is simply a request for expunge */
            continue;
        }

        if (mail_transaction_log_sort_expunges(expunges_r, data,
                               hdr->size) < 0) {
            mail_transaction_log_view_set_corrupted(view->log_view,
                "Corrupted expunge record");
            ret = -1;
            break;
        }
    }

    if (ret < 0) {
        array_free(expunges_r);
        return -1;
    }

    /* convert UIDs to sequences */
    src = dest = array_get_modifiable(expunges_r, &count);
    src_end = src + count;
    for (; src != src_end; src++) {
        ret = mail_index_lookup_uid_range(view, src->seq1,
                          src->seq2,
                          &dest->seq1,
                          &dest->seq2);
        i_assert(ret == 0);

        if (dest->seq1 == 0)
            count--;
        else
            dest++;
    }
    array_delete(expunges_r, count, array_count(expunges_r) - count);
    return 0;
}

static void mail_index_view_hdr_drop_appends(struct mail_index_view *view,
                         struct mail_index_map *map)
{
    /* Keep message count the same. */
    map->hdr.next_uid = view->hdr.next_uid;
    map->hdr.messages_count = view->hdr.messages_count;

    /* Keep the old message flag counts also, although they may be
       somewhat stale already. We just don't want them to be more than
       our old messages_count. */
    map->hdr.recent_messages_count = view->hdr.recent_messages_count;
    map->hdr.seen_messages_count = view->hdr.seen_messages_count;
    map->hdr.deleted_messages_count = view->hdr.deleted_messages_count;
}

#ifdef DEBUG
static void mail_index_view_check(struct mail_index_view *view)
{
    unsigned int i, del = 0, recent = 0, seen = 0;

    i_assert(view->hdr.messages_count == view->map->records_count);
    i_assert(view->hdr.deleted_messages_count ==
         view->map->hdr.deleted_messages_count);
    i_assert(view->hdr.recent_messages_count ==
         view->map->hdr.recent_messages_count);
    i_assert(view->hdr.seen_messages_count ==
         view->map->hdr.seen_messages_count);

    for (i = 0; i < view->map->records_count; i++) {
        const struct mail_index_record *rec;

        rec = MAIL_INDEX_MAP_IDX(view->map, i);

        if (rec->flags & MAIL_DELETED) {
            i_assert(rec->uid >= view->hdr.first_deleted_uid_lowwater);
            del++;
        }
        if (rec->flags & MAIL_RECENT) {
            i_assert(rec->uid >= view->hdr.first_recent_uid_lowwater);
            recent++;
        }
        if (rec->flags & MAIL_SEEN)
            seen++;
        else
            i_assert(rec->uid >= view->hdr.first_unseen_uid_lowwater);
    }
    i_assert(del == view->hdr.deleted_messages_count);
    i_assert(recent == view->hdr.recent_messages_count);
    i_assert(seen == view->hdr.seen_messages_count);
}
#endif

#define MAIL_INDEX_VIEW_VISIBLE_FLAGS_MASK \
    (MAIL_INDEX_SYNC_TYPE_FLAGS | \
     MAIL_INDEX_SYNC_TYPE_KEYWORD_RESET | \
     MAIL_INDEX_SYNC_TYPE_KEYWORD_ADD | MAIL_INDEX_SYNC_TYPE_KEYWORD_REMOVE)

#define MAIL_TRANSACTION_VISIBLE_SYNC_MASK \
    (MAIL_TRANSACTION_EXPUNGE | MAIL_TRANSACTION_APPEND | \
     MAIL_TRANSACTION_FLAG_UPDATE | MAIL_TRANSACTION_KEYWORD_UPDATE | \
     MAIL_TRANSACTION_KEYWORD_RESET)

#define VIEW_IS_SYNCED_TO_SAME(hdr, tail_seq, tail_offset) \
    ((hdr)->log_file_seq == (tail_seq) && \
     (hdr)->log_file_head_offset == (tail_offset))

int mail_index_view_sync_begin(struct mail_index_view *view,
                               enum mail_index_view_sync_type sync_type,
                   struct mail_index_view_sync_ctx **ctx_r)
{
    struct mail_index_view_sync_ctx *ctx;
    struct mail_index_map *map;
    uint32_t tail_seq;
    uoff_t tail_offset;
    enum mail_transaction_type visible_mask = 0;
    ARRAY_TYPE(seq_range) expunges = ARRAY_INIT;
    bool drop_appends;

    i_assert(!view->syncing);
    i_assert(view->transactions == 0);

    if (mail_index_view_lock_head(view) < 0)
        return -1;

    if (sync_type == MAIL_INDEX_VIEW_SYNC_TYPE_ALL) {
        /* get list of all expunges first */
        if (view_sync_get_expunges(view, &expunges) < 0)
            return -1;
    }

    /* only flags, appends and expunges can be left to be synced later */
    switch (sync_type) {
    case MAIL_INDEX_VIEW_SYNC_TYPE_ALL:
        visible_mask = MAIL_TRANSACTION_VISIBLE_SYNC_MASK;
        break;
    case MAIL_INDEX_VIEW_SYNC_TYPE_NOAPPENDS_NOEXPUNGES:
        visible_mask = MAIL_TRANSACTION_VISIBLE_SYNC_MASK &
            ~(MAIL_TRANSACTION_EXPUNGE | MAIL_TRANSACTION_APPEND);
        break;
    case MAIL_INDEX_VIEW_SYNC_TYPE_NOEXPUNGES:
        visible_mask = MAIL_TRANSACTION_VISIBLE_SYNC_MASK &
            ~MAIL_TRANSACTION_EXPUNGE;
        break;
    }

    if (view_sync_set_log_view_range(view) < 0) {
        if (array_is_created(&expunges))
            array_free(&expunges);
        return -1;
    }

    ctx = i_new(struct mail_index_view_sync_ctx, 1);
    ctx->view = view;
    ctx->visible_sync_mask = visible_mask;
    ctx->expunges = expunges;
    mail_index_sync_map_init(&ctx->sync_map_ctx, view,
                 MAIL_INDEX_SYNC_HANDLER_VIEW);

    if (sync_type == MAIL_INDEX_VIEW_SYNC_TYPE_ALL) {
        view->sync_new_map = view->index->map;
        view->sync_new_map->refcount++;

        /* since we're syncing everything, the counters get fixed */
        view->broken_counters = FALSE;

        /* keep the old mapping without expunges until we're
           fully synced */
    } else {
        /* We need a private copy of the map if we don't want to
           sync expunges.

           If view's map is the head map, it means that it contains
           already all the latest changes and there's no need for us
           to apply any changes to it. This can only happen if there
           hadn't been any expunges. */
        uint32_t old_records_count = view->map->records_count;

        if (view->map != view->index->map) {
            /* Using non-head mapping. We have to apply
               transactions to it to get latest changes into it. */
            ctx->sync_map_update = TRUE;
        }

        /* Unless map was synced at the exact same position as
           view, the message flags can't be reliably used to
           update flag counters. note that map->hdr may contain
           old information if another process updated the
           index file since. */
        if (view->map->mmap_base != NULL) {
            const struct mail_index_header *hdr;

            hdr = view->map->mmap_base;
            view->map->hdr = *hdr;
        }

        view_sync_get_tail(view, &tail_seq, &tail_offset);
        ctx->sync_map_ctx.unreliable_flags =
            !VIEW_IS_SYNCED_TO_SAME(&view->map->hdr,
                        tail_seq, tail_offset);

        drop_appends = ctx->sync_map_update || sync_type ==
            MAIL_INDEX_VIEW_SYNC_TYPE_NOAPPENDS_NOEXPUNGES;
        if (drop_appends) {
            /* Copy only the mails that we see currently, since
               we're going to append the new ones when we see
               their transactions. */
            i_assert(view->map->records_count >=
                 view->hdr.messages_count);
            view->map->records_count = view->hdr.messages_count;
        }

#ifdef DEBUG
        if (!ctx->sync_map_ctx.unreliable_flags) {
            i_assert(view->map->hdr.messages_count ==
                 view->hdr.messages_count);
            mail_index_view_check(view);
        }
#endif

        map = mail_index_map_clone(view->map);
        view->map->records_count = old_records_count;
        mail_index_unmap(view->index, &view->map);
        view->map = map;

        if (drop_appends) {
            /* Start the sync using our old view's header.
               The old view->hdr may differ from map->hdr if
               another view sharing the map with us had synced
               itself. */
            i_assert(map->hdr_base == map->hdr_copy_buf->data);
            mail_index_view_hdr_drop_appends(view, map);
        }
        view->hdr = map->hdr;

        i_assert(map->records_count == map->hdr.messages_count);
    }

    /* Syncing the view invalidates all previous looked up records.
       Unreference the mappings this view keeps because of them. */
    mail_index_view_unref_maps(view);
    view->syncing = TRUE;

    *ctx_r = ctx;
    return 0;
}

static bool view_sync_area_find(ARRAY_TYPE(view_log_sync_area) *sync_arr,
                uint32_t seq, uoff_t offset)
{
    const struct mail_index_view_log_sync_area *syncs;
    unsigned int i, count;

    if (!array_is_created(sync_arr))
        return FALSE;

    syncs = array_get(sync_arr, &count);
    for (i = 0; i < count; i++) {
        if (syncs[i].log_file_offset <= offset &&
            offset - syncs[i].log_file_offset < syncs[i].length &&
            syncs[i].log_file_seq == seq)
            return TRUE;
    }

    return FALSE;
}

static bool
mail_index_view_sync_want(struct mail_index_view_sync_ctx *ctx,
              const struct mail_transaction_header *hdr)
{
        struct mail_index_view *view = ctx->view;
    uint32_t seq;
    uoff_t offset, next_offset;

    mail_transaction_log_view_get_prev_pos(view->log_view, &seq, &offset);
    next_offset = offset + sizeof(*hdr) + hdr->size;

    switch (hdr->type & MAIL_TRANSACTION_TYPE_MASK) {
    case MAIL_TRANSACTION_APPEND:
        if ((ctx->visible_sync_mask & MAIL_TRANSACTION_APPEND) == 0) {
            i_assert(!LOG_IS_BEFORE(seq, offset,
                        view->log_file_append_seq,
                        view->log_file_append_offset));
            if (!ctx->skipped_appends) {
                view->log_file_append_seq = seq;
                view->log_file_append_offset = offset;
                ctx->skipped_appends = TRUE;
            }
            return FALSE;
        }
        if (LOG_IS_BEFORE(seq, offset, view->log_file_append_seq,
                  view->log_file_append_offset)) {
            /* already synced */
            return FALSE;
        }
        break;
    case MAIL_TRANSACTION_EXPUNGE:
        if ((hdr->type & MAIL_TRANSACTION_EXTERNAL) == 0) {
            /* expunge request. this will be ignored */
            break;
        }
        if ((ctx->visible_sync_mask & MAIL_TRANSACTION_EXPUNGE) == 0) {
            i_assert(!LOG_IS_BEFORE(seq, offset,
                        view->log_file_expunge_seq,
                        view->log_file_expunge_offset));
            if (!ctx->skipped_expunges) {
                view->log_file_expunge_seq = seq;
                view->log_file_expunge_offset = offset;
                ctx->skipped_expunges = TRUE;
            }
            return FALSE;
        }
        if (LOG_IS_BEFORE(seq, offset, view->log_file_expunge_seq,
                  view->log_file_expunge_offset)) {
            /* already synced */
            return FALSE;
        }
        break;
    default:
        if ((hdr->type & ctx->visible_sync_mask) != 0)
            break;
        if ((hdr->type & MAIL_TRANSACTION_VISIBLE_SYNC_MASK) == 0)
            break;

        /* visible record that we want to skip */
        return FALSE;
    }

    if (LOG_IS_BEFORE(seq, offset, view->log_file_head_seq,
              view->log_file_head_offset)) {
        /* already synced */
        return FALSE;
    }

    view->log_file_head_seq = seq;
    view->log_file_head_offset = next_offset;
    return TRUE;
}

static int
mail_index_view_sync_get_next_transaction(struct mail_index_view_sync_ctx *ctx)
{
        struct mail_transaction_log_view *log_view = ctx->view->log_view;
    struct mail_index_view *view = ctx->view;
    const struct mail_transaction_header *hdr;
    uint32_t seq;
    uoff_t offset;
    int ret;
    bool synced_to_map;

    for (;;) {
        /* Get the next transaction from log. */
        ret = mail_transaction_log_view_next(log_view, &ctx->hdr,
                             &ctx->data);
        if (ret <= 0) {
            if (ret < 0)
                return -1;

            ctx->hdr = NULL;
            ctx->last_read = TRUE;
            return 0;
        }

        hdr = ctx->hdr;
        if (!mail_index_view_sync_want(ctx, hdr)) {
            /* This is a visible record that we don't want to
               sync. */
            continue;
        }

        mail_transaction_log_view_get_prev_pos(log_view, &seq, &offset);

        /* If we started from a map that we didn't create ourself,
           some of the transactions may already be synced. at the end
           of this view sync we'll update file_seq=0 so that this check
           always becomes FALSE for subsequent syncs. */
        synced_to_map = view->map->hdr.log_file_seq != 0 &&
            !LOG_IS_BEFORE(seq, offset,
                       view->map->hdr.log_file_seq,
                       view->map->hdr.log_file_head_offset);

        /* Apply transaction to view's mapping if needed (meaning we
           didn't just re-map the view to head mapping). */
        if (ctx->sync_map_update && !synced_to_map) {
            i_assert((hdr->type & MAIL_TRANSACTION_EXPUNGE) == 0 ||
                 (hdr->type & MAIL_TRANSACTION_EXTERNAL) == 0);

            if (mail_index_sync_record(&ctx->sync_map_ctx,
                           hdr, ctx->data) < 0)
                return -1;
        }

        if ((hdr->type & ctx->visible_sync_mask) == 0) {
            /* non-visible change that we just wanted to update
               to map. */
            continue;
        }

        /* skip changes committed by hidden transactions (eg. in IMAP
           store +flags.silent command) */
        if (view_sync_area_find(&view->syncs_hidden, seq, offset))
            continue;
        break;
    }
    return 1;
}

#define FLAG_UPDATE_IS_INTERNAL(u) \
    ((((u)->add_flags | (u)->remove_flags) & \
      ~(MAIL_INDEX_MAIL_FLAG_DIRTY | MAIL_RECENT)) == 0)

static int
mail_index_view_sync_get_rec(struct mail_index_view_sync_ctx *ctx,
                 struct mail_index_view_sync_rec *rec)
{
    const struct mail_transaction_header *hdr = ctx->hdr;
    const void *data = ctx->data;

    switch (hdr->type & MAIL_TRANSACTION_TYPE_MASK) {
    case MAIL_TRANSACTION_APPEND: {
        /* data contains the appended records, but we don't care */
        rec->type = MAIL_INDEX_SYNC_TYPE_APPEND;
        rec->uid1 = rec->uid2 = 0;
        ctx->data_offset += hdr->size;
        break;
    }
    case MAIL_TRANSACTION_EXPUNGE: {
        const struct mail_transaction_expunge *exp =
            CONST_PTR_OFFSET(data, ctx->data_offset);

        if ((hdr->type & MAIL_TRANSACTION_EXTERNAL) == 0) {
            /* this is simply a request for expunge */
            ctx->data_offset = ctx->hdr->size;
            return 0;
        }

        /* data contains mail_transaction_expunge[] */
        rec->type = MAIL_INDEX_SYNC_TYPE_EXPUNGE;
        rec->uid1 = exp->uid1;
        rec->uid2 = exp->uid2;

        ctx->data_offset += sizeof(*exp);
        break;
    }
    case MAIL_TRANSACTION_FLAG_UPDATE: {
        const struct mail_transaction_flag_update *update =
            CONST_PTR_OFFSET(data, ctx->data_offset);

        /* data contains mail_transaction_flag_update[] */
        for (;;) {
            ctx->data_offset += sizeof(*update);
            if (!FLAG_UPDATE_IS_INTERNAL(update))
                break;

            /* skip internal flag changes */
            if (ctx->data_offset == ctx->hdr->size)
                return 0;

            update = CONST_PTR_OFFSET(data, ctx->data_offset);
        }

        rec->type = MAIL_INDEX_SYNC_TYPE_FLAGS;
        rec->uid1 = update->uid1;
        rec->uid2 = update->uid2;
        break;
    }
    case MAIL_TRANSACTION_KEYWORD_UPDATE: {
        const struct mail_transaction_keyword_update *update = data;
        const uint32_t *uids;

        /* data contains mail_transaction_keyword_update header,
           the keyword name and an array of { uint32_t uid1, uid2; } */

        if (ctx->data_offset == 0) {
            /* skip over the header and name */
            ctx->data_offset = sizeof(*update) + update->name_size;
            if ((ctx->data_offset % 4) != 0)
                ctx->data_offset += 4 - (ctx->data_offset % 4);
        }

        uids = CONST_PTR_OFFSET(data, ctx->data_offset);
        rec->type = MAIL_INDEX_SYNC_TYPE_KEYWORD_ADD;
        rec->uid1 = uids[0];
        rec->uid2 = uids[1];

        ctx->data_offset += sizeof(uint32_t) * 2;
        break;
    }
    case MAIL_TRANSACTION_KEYWORD_RESET: {
        const struct mail_transaction_keyword_reset *reset =
            CONST_PTR_OFFSET(data, ctx->data_offset);

        /* data contains mail_transaction_keyword_reset[] */
        rec->type = MAIL_INDEX_SYNC_TYPE_KEYWORD_RESET;
        rec->uid1 = reset->uid1;
        rec->uid2 = reset->uid2;
        ctx->data_offset += sizeof(*reset);
        break;
    }
    default:
        i_unreached();
    }
    return 1;
}

int mail_index_view_sync_next(struct mail_index_view_sync_ctx *ctx,
                  struct mail_index_view_sync_rec *sync_rec)
{
    int ret;

    do {
        if (ctx->hdr == NULL || ctx->data_offset == ctx->hdr->size) {
            ret = mail_index_view_sync_get_next_transaction(ctx);
            if (ret <= 0)
                return ret;

            ctx->data_offset = 0;
        }
    } while (!mail_index_view_sync_get_rec(ctx, sync_rec));

    return 1;
}

void mail_index_view_sync_get_expunges(struct mail_index_view_sync_ctx *ctx,
                       const ARRAY_TYPE(seq_range) **expunges_r)
{
    *expunges_r = &ctx->expunges;
}

static void
mail_index_view_sync_clean_log_syncs(struct mail_index_view *view)
{
    const struct mail_index_view_log_sync_area *syncs;
    uint32_t tail_seq;
    uoff_t tail_offset;
    unsigned int i, count;

    if (!array_is_created(&view->syncs_hidden))
        return;

    /* Clean up to view's tail */
    view_sync_get_tail(view, &tail_seq, &tail_offset);

    syncs = array_get(&view->syncs_hidden, &count);
    for (i = 0; i < count; i++) {
        if ((syncs[i].log_file_offset + syncs[i].length > tail_offset &&
                     syncs[i].log_file_seq == tail_seq) ||
            syncs[i].log_file_seq > tail_seq)
            break;
    }
    if (i > 0)
        array_delete(&view->syncs_hidden, 0, i);
}

void mail_index_view_sync_end(struct mail_index_view_sync_ctx **_ctx)
{
        struct mail_index_view_sync_ctx *ctx = *_ctx;
        struct mail_index_view *view = ctx->view;

    i_assert(view->syncing);

    *_ctx = NULL;

    if (!ctx->last_read) {
        /* we didn't sync everything */
        view->inconsistent = TRUE;
    }

    if (view->sync_new_map != NULL) {
        mail_index_unmap(view->index, &view->map);
        view->map = view->sync_new_map;
        view->sync_new_map = NULL;
    }

    if (!ctx->skipped_expunges) {
        view->log_file_expunge_seq = view->log_file_head_seq;
        view->log_file_expunge_offset = view->log_file_head_offset;
    }
    if (!ctx->skipped_appends) {
        view->log_file_append_seq = view->log_file_head_seq;
        view->log_file_append_offset = view->log_file_head_offset;
    }

    if (ctx->sync_map_update) {
        /* log offsets have no meaning in views. make sure they're not
           tried to be used wrong by setting them to zero. */
        view->map->hdr.log_file_seq = 0;
        view->map->hdr.log_file_head_offset = 0;
        view->map->hdr.log_file_tail_offset = 0;
    }
    view->hdr = view->map->hdr;

    mail_index_sync_map_deinit(&ctx->sync_map_ctx);
    mail_index_view_sync_clean_log_syncs(ctx->view);

#ifdef DEBUG
    if (!view->broken_counters && !ctx->sync_map_ctx.unreliable_flags)
        mail_index_view_check(view);
#endif

    /* set log view to empty range so unneeded memory gets freed */
    (void)mail_transaction_log_view_set(view->log_view,
                        view->log_file_head_seq,
                        view->log_file_head_offset,
                        view->log_file_head_seq,
                        view->log_file_head_offset);

    if (array_is_created(&ctx->expunges))
        array_free(&ctx->expunges);

    view->syncing = FALSE;
    i_free(ctx);
}

void mail_index_view_add_hidden_transaction(struct mail_index_view *view,
                        uint32_t log_file_seq,
                        uoff_t log_file_offset,
                        unsigned int length)
{
    struct mail_index_view_log_sync_area *area;

    if (!array_is_created(&view->syncs_hidden))
        i_array_init(&view->syncs_hidden, 32);

    area = array_append_space(&view->syncs_hidden);
    area->log_file_seq = log_file_seq;
    area->log_file_offset = log_file_offset;
    area->length = length;
}