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/*-
* Copyright (c) 2008-2012 WiredTiger, Inc.
* All rights reserved.
*
* See the file LICENSE for redistribution information.
*/
#include "wt_internal.h"
/*
* __wt_merge_update_tree --
* Merge a set of chunks and create a new one.
* Must be called with the LSM lock held.
*/
static int
__lsm_merge_update_tree(WT_SESSION_IMPL *session,
WT_LSM_TREE *lsm_tree, int nchunks, WT_LSM_CHUNK **chunkp)
{
WT_LSM_CHUNK *chunk;
size_t chunk_sz;
int i, j;
if (nchunks > lsm_tree->old_avail) {
chunk_sz = sizeof(*lsm_tree->old_chunks);
WT_RET(__wt_realloc(session,
&lsm_tree->old_alloc,
chunk_sz * WT_MAX(10, lsm_tree->nold_chunks + 2 * nchunks),
&lsm_tree->old_chunks));
lsm_tree->old_avail += (int)(lsm_tree->old_alloc / chunk_sz) -
lsm_tree->nold_chunks;
lsm_tree->nold_chunks = (int)(lsm_tree->old_alloc / chunk_sz);
}
/* Copy entries one at a time, so we can reuse gaps in the list. */
for (i = j = 0; j < nchunks && i < lsm_tree->nold_chunks; i++) {
if (lsm_tree->old_chunks[i] == NULL) {
lsm_tree->old_chunks[i] = lsm_tree->chunk[j++];
--lsm_tree->old_avail;
}
}
WT_ASSERT(session, j == nchunks);
/* Update the current chunk list. */
memmove(lsm_tree->chunk + 1, lsm_tree->chunk + nchunks,
(lsm_tree->nchunks - nchunks) * sizeof(*lsm_tree->chunk));
lsm_tree->nchunks -= nchunks - 1;
memset(lsm_tree->chunk + lsm_tree->nchunks, 0,
(nchunks - 1) * sizeof(*lsm_tree->chunk));
WT_RET(__wt_calloc_def(session, 1, &chunk));
lsm_tree->chunk[0] = chunk;
lsm_tree->dsk_gen++;
*chunkp = chunk;
return (0);
}
/*
* __wt_lsm_major_merge --
* Merge a set of chunks of an LSM tree including the oldest.
*/
int
__wt_lsm_major_merge(WT_SESSION_IMPL *session, WT_LSM_TREE *lsm_tree)
{
WT_BLOOM *bloom;
WT_CURSOR *src, *dest;
WT_DECL_ITEM(bbuf);
WT_DECL_RET;
WT_ITEM key, value;
WT_LSM_CHUNK *chunk;
WT_SESSION *wt_session;
const char *dest_uri;
uint64_t record_count;
int dest_id, nchunks;
src = dest = NULL;
/*
* TODO: describe the dace with lsm_tree->lock here to avoid holding
* the tree locked while a merge is in progress.
*/
/*
* Take a copy of the latest chunk id. This value needs to be atomically
* read. We need a copy, since other threads may alter the chunk count
* while we are doing a merge.
*/
nchunks = lsm_tree->nchunks - 1;
/*
* If there aren't any chunks to merge, or some of the chunks aren't
* yet written, we're done. A non-zero error indicates that the worker
* should assume there is no work to do: if there are unwritten chunks,
* the worker should write them immediately.
*/
if (nchunks <= 1)
return (WT_NOTFOUND);
/*
* We have a limited number of hazard references, and we want to bound
* the amount of work in the merge.
*/
nchunks = WT_MIN((int)S2C(session)->hazard_size / 2, nchunks);
while (nchunks > 1 &&
(!F_ISSET(lsm_tree->chunk[nchunks - 1], WT_LSM_CHUNK_ONDISK) ||
lsm_tree->chunk[nchunks - 1]->ncursor > 0))
--nchunks;
if (nchunks <= 1)
return (0);
/* Allocate an ID for the merge. */
dest_id = WT_ATOMIC_ADD(lsm_tree->last, 1);
printf("Merging first %d chunks into %d\n", nchunks, dest_id);
WT_RET(__wt_scr_alloc(session, 0, &bbuf));
WT_RET(__wt_lsm_tree_bloom_name(session, lsm_tree, dest_id, bbuf));
/* TODO sum the record count in the chunks */
record_count = 100000;
WT_RET(__wt_bloom_create(session, bbuf->data, NULL, record_count,
lsm_tree->bloom_factor, lsm_tree->bloom_k, &bloom));
/*
* Special setup for the merge cursor:
* first, reset to open the dependent cursors;
* then restrict the cursor to a specific number of chunks;
* then set MERGE so the cursor doesn't track updates to the tree.
*/
wt_session = &session->iface;
WT_RET(wt_session->open_cursor(
wt_session, lsm_tree->name, NULL, NULL, &src));
F_SET(src, WT_CURSTD_RAW);
WT_ERR(__wt_clsm_init_merge(src, nchunks));
WT_WITH_SCHEMA_LOCK(session, ret = __wt_lsm_tree_create_chunk(
session, lsm_tree, dest_id, &dest_uri));
WT_ERR(ret);
WT_ERR(wt_session->open_cursor(
wt_session, dest_uri, NULL, "raw,bulk", &dest));
for (record_count = 0; (ret = src->next(src)) == 0; record_count++) {
WT_ERR(src->get_key(src, &key));
dest->set_key(dest, &key);
WT_ERR(src->get_value(src, &value));
dest->set_value(dest, &value);
WT_ERR(dest->insert(dest));
WT_ERR(__wt_bloom_insert(bloom, &key));
}
WT_ERR_NOTFOUND_OK(ret);
/* We've successfully created the new chunk. Now install it. */
WT_TRET(src->close(src));
WT_TRET(dest->close(dest));
WT_TRET(__wt_bloom_finalize(bloom));
WT_TRET(__wt_bloom_close(bloom));
src = dest = NULL;
bloom = NULL;
WT_ERR(ret);
__wt_spin_lock(session, &lsm_tree->lock);
ret = __lsm_merge_update_tree(session, lsm_tree, nchunks, &chunk);
chunk->uri = dest_uri;
dest_uri = NULL;
chunk->bloom_uri = __wt_buf_steal(session, bbuf, 0);
chunk->count = record_count;
F_SET(chunk, WT_LSM_CHUNK_ONDISK);
ret = __wt_lsm_meta_write(session, lsm_tree);
__wt_spin_unlock(session, &lsm_tree->lock);
printf("Merge done\n");
err: if (src != NULL)
WT_TRET(src->close(src));
if (dest != NULL)
WT_TRET(dest->close(dest));
if (bloom != NULL)
WT_TRET(__wt_bloom_close(bloom));
__wt_scr_free(&bbuf);
__wt_free(session, dest_uri);
if (ret != 0)
printf("Merge failed with %s\n", wiredtiger_strerror(ret));
return (ret);
}
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