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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 2008-2011 WiredTiger, Inc.
* All rights reserved.
*/
#include "wt_internal.h"
/*
* 7-bit ASCII, with English language frequencies.
*
* Based on "Case-sensitive letter and bigram frequency counts from large-scale
* English corpora"
* Michael N. Jones and D.J.K. Mewhort
* Queen's University, Kingston, Ontario, Canada
* Behavior Research Methods, Instruments, & Computers 2004, 36 (3), 388-396
*
* Additionally supports space and tab characters; space is the most common
* character in text where it occurs, and tab appears about as frequently as
* 'a' and 'n' in text where it occurs.
*/
struct __wt_huffman_table {
uint32_t symbol;
uint32_t frequency;
};
static const struct __wt_huffman_table __wt_huffman_nytenglish[] = {
/* nul */ { 0x00, 0 }, /* For an escape character. */
/* ht */ { 0x09, 5263779 },
/* sp */ { 0x20, 8000000 },
/* ! */ { 0x21, 2178 },
/* " */ { 0x22, 284671 },
/* # */ { 0x23, 10 },
/* $ */ { 0x24, 51572 },
/* % */ { 0x25, 1993 },
/* & */ { 0x26, 6523 },
/* ' */ { 0x27, 204497 },
/* ( */ { 0x28, 53398 },
/* ) */ { 0x29, 53735 },
/* * */ { 0x2a, 20716 },
/* + */ { 0x2b, 309 },
/* , */ { 0x2c, 984969 },
/* - */ { 0x2d, 252302 },
/* . */ { 0x2e, 946136 },
/* / */ { 0x2f, 8161 },
/* 0 */ { 0x30, 546233 },
/* 1 */ { 0x31, 460946 },
/* 2 */ { 0x32, 333499 },
/* 3 */ { 0x33, 187606 },
/* 4 */ { 0x34, 192528 },
/* 5 */ { 0x35, 374413 },
/* 6 */ { 0x36, 153865 },
/* 7 */ { 0x37, 120094 },
/* 8 */ { 0x38, 182627 },
/* 9 */ { 0x39, 282364 },
/* : */ { 0x3a, 54036 },
/* ; */ { 0x3b, 36727 },
/* < */ { 0x3c, 82 },
/* = */ { 0x3d, 22 },
/* > */ { 0x3e, 83 },
/* ? */ { 0x3f, 12357 },
/* @ */ { 0x40, 1 },
/* A */ { 0x41, 280937 },
/* B */ { 0x42, 169474 },
/* C */ { 0x43, 229363 },
/* D */ { 0x44, 129632 },
/* E */ { 0x45, 138443 },
/* F */ { 0x46, 100751 },
/* G */ { 0x47, 93212 },
/* H */ { 0x48, 123632 },
/* I */ { 0x49, 223312 },
/* J */ { 0x4a, 78706 },
/* K */ { 0x4b, 46580 },
/* L */ { 0x4c, 106984 },
/* M */ { 0x4d, 259474 },
/* N */ { 0x4e, 205409 },
/* O */ { 0x4f, 105700 },
/* P */ { 0x50, 144239 },
/* Q */ { 0x51, 11659 },
/* R */ { 0x52, 146448 },
/* S */ { 0x53, 304971 },
/* T */ { 0x54, 325462 },
/* U */ { 0x55, 57488 },
/* V */ { 0x56, 31053 },
/* W */ { 0x57, 107195 },
/* X */ { 0x58, 7578 },
/* Y */ { 0x59, 94297 },
/* Z */ { 0x5a, 5610 },
/* [ */ { 0x5b, 1 },
/* \ */ { 0x5c, 1 },
/* ] */ { 0x5d, 1 },
/* ^ */ { 0x5e, 1 },
/* _ */ { 0x5f, 1 },
/* ` */ { 0x60, 1 },
/* a */ { 0x61, 5263779 },
/* b */ { 0x62, 866156 },
/* c */ { 0x63, 1960412 },
/* d */ { 0x64, 2369820 },
/* e */ { 0x65, 7741842 },
/* f */ { 0x66, 1296925 },
/* g */ { 0x67, 1206747 },
/* h */ { 0x68, 2955858 },
/* i */ { 0x69, 4527332 },
/* j */ { 0x6a, 65856 },
/* k */ { 0x6b, 460788 },
/* l */ { 0x6c, 2553152 },
/* m */ { 0x6d, 1467376 },
/* n */ { 0x6e, 4535545 },
/* o */ { 0x6f, 4729266 },
/* p */ { 0x70, 1255579 },
/* q */ { 0x71, 54221 },
/* r */ { 0x72, 4137949 },
/* s */ { 0x73, 4186210 },
/* t */ { 0x74, 5507692 },
/* u */ { 0x75, 1613323 },
/* v */ { 0x76, 653370 },
/* w */ { 0x77, 1015656 },
/* x */ { 0x78, 123577 },
/* y */ { 0x79, 1062040 },
/* z */ { 0x7a, 66423 },
/* { */ { 0x7b, 1 },
/* | */ { 0x7c, 1 },
/* } */ { 0x7d, 1 },
/* ~ */ { 0x7e, 1 }
};
static int __wt_huffman_read(WT_SESSION_IMPL *,
WT_CONFIG_ITEM *, struct __wt_huffman_table **, u_int *, u_int *);
/*
* __wt_btree_huffman_open --
* Configure Huffman encoding for the tree.
*/
int
__wt_btree_huffman_open(WT_SESSION_IMPL *session, const char *config)
{
WT_BTREE *btree;
u_int entries, numbytes;
struct __wt_huffman_table *table;
WT_CONFIG_ITEM key_conf, value_conf;
int ret;
btree = session->btree;
WT_RET(__wt_config_getones(session, config, "huffman_key", &key_conf));
WT_RET(__wt_config_getones(
session, config, "huffman_value", &value_conf));
if (key_conf.len == 0 && value_conf.len == 0)
return (0);
switch (btree->type) { /* Check file type compatibility. */
case BTREE_COL_FIX:
WT_RET_MSG(session, EINVAL,
"fixed-size column-store files may not be Huffman encoded");
case BTREE_COL_VAR:
if (key_conf.len != 0)
WT_RET_MSG(session, EINVAL,
"the keys of variable-length column-store files "
"may not be Huffman encoded");
break;
case BTREE_ROW:
break;
}
if (strncasecmp(key_conf.str, "english", key_conf.len) == 0) {
struct __wt_huffman_table
copy[WT_ELEMENTS(__wt_huffman_nytenglish)];
memcpy(copy,
__wt_huffman_nytenglish, sizeof(__wt_huffman_nytenglish));
WT_RET(__wt_huffman_open(session, copy,
WT_ELEMENTS(__wt_huffman_nytenglish),
1, &btree->huffman_key));
/* Check for a shared key/value table. */
if (strncasecmp(
value_conf.str, "english", value_conf.len) == 0) {
btree->huffman_value = btree->huffman_key;
return (0);
}
} else {
WT_RET(__wt_huffman_read(
session, &key_conf, &table, &entries, &numbytes));
ret = __wt_huffman_open(session, table,
entries, numbytes, &btree->huffman_key);
__wt_free(session, table);
if (ret != 0)
return (ret);
/* Check for a shared key/value table. */
if (value_conf.len != 0 && key_conf.len == value_conf.len &&
memcmp(key_conf.str, value_conf.str, key_conf.len) == 0) {
btree->huffman_value = btree->huffman_key;
return (0);
}
}
if (strncasecmp(value_conf.str, "english", value_conf.len) == 0) {
struct __wt_huffman_table
copy[WT_ELEMENTS(__wt_huffman_nytenglish)];
memcpy(copy,
__wt_huffman_nytenglish, sizeof(__wt_huffman_nytenglish));
WT_RET(__wt_huffman_open(session, copy,
WT_ELEMENTS(__wt_huffman_nytenglish),
1, &btree->huffman_value));
} else {
WT_RET(__wt_huffman_read(
session, &value_conf, &table, &entries, &numbytes));
ret = __wt_huffman_open(session, table,
entries, numbytes, &btree->huffman_value);
__wt_free(session, table);
if (ret != 0)
return (ret);
}
return (0);
}
/*
* __wt_huffman_read --
* Read a Huffman table from a file.
*/
static int
__wt_huffman_read(WT_SESSION_IMPL *session, WT_CONFIG_ITEM *ip,
struct __wt_huffman_table **tablep, u_int *entriesp, u_int *numbytesp)
{
struct __wt_huffman_table *table, *tp;
FILE *fp;
uint64_t symbol, frequency;
u_int entries, lineno, max;
int ret;
char *file;
ret = 0;
file = NULL;
table = NULL;
/*
* UTF-8 table is 256 bytes, with a range of 0-255.
* UTF-16 is 128KB (2 * 65536) bytes, with a range of 0-65535.
*/
if (strncasecmp(ip->str, "utf8", 4) == 0) {
entries = UINT8_MAX;
max = UINT8_MAX - 1;
*numbytesp = 1;
WT_RET(__wt_calloc_def(session, entries, &table));
if (ip->len == 4)
WT_ERR_MSG(session, EINVAL,
"no Huffman table file name specified");
WT_ERR(__wt_calloc_def(session, ip->len, &file));
memcpy(file, ip->str + 4, ip->len - 4);
} else if (strncasecmp(ip->str, "utf16", 5) == 0) {
entries = UINT16_MAX;
max = UINT16_MAX - 1;
*numbytesp = 2;
WT_RET(__wt_calloc_def(session, entries, &table));
if (ip->len == 5)
WT_ERR_MSG(session, EINVAL,
"no Huffman table file name specified");
WT_ERR(__wt_calloc_def(session, ip->len, &file));
memcpy(file, ip->str + 5, ip->len - 5);
} else {
WT_ERR_MSG(session, EINVAL,
"unknown Huffman configuration value %.*s",
(int)ip->len, ip->str);
}
if ((fp = fopen(file, "r")) == NULL)
WT_ERR_MSG(session, __wt_errno(),
"unable to read Huffman table file %.*s",
(int)ip->len, ip->str);
for (tp = table, lineno = 1; (ret =
fscanf(fp, "%" SCNu64 " %" SCNu64, &symbol, &frequency)) != EOF;
++tp, ++lineno) {
if (lineno > entries)
WT_ERR_MSG(session, EINVAL,
"Huffman table file %.*s is corrupted, "
"more than %" PRIu32 " entries",
(int)ip->len, ip->str, entries);
if (ret != 2)
WT_ERR_MSG(session, EINVAL,
"line %u of Huffman table file %.*s is corrupted: "
"expected two unsigned integral values",
lineno, (int)ip->len, ip->str);
if (symbol > max)
WT_ERR_MSG(session, EINVAL,
"line %u of Huffman table file %.*s is corrupted: "
"symbol larger than maximum value of %u",
lineno, (int)ip->len, ip->str, max);
if (frequency > UINT32_MAX)
WT_ERR_MSG(session, EINVAL,
"line %u of Huffman table file %.*s is corrupted: "
"frequency larger than maximum value of %" PRIu32,
lineno, (int)ip->len, ip->str, UINT32_MAX);
tp->symbol = (uint32_t)symbol;
tp->frequency = (uint32_t)frequency;
}
*entriesp = lineno - 1;
*tablep = table;
return (0);
err: __wt_free(session, file);
__wt_free(session, table);
return (ret);
}
/*
* __wt_btree_huffman_close --
* Close the Huffman tables.
*/
void
__wt_btree_huffman_close(WT_SESSION_IMPL *session)
{
WT_BTREE *btree;
btree = session->btree;
if (btree->huffman_key != NULL) {
/* Key and data may use the same table, only close it once. */
if (btree->huffman_value == btree->huffman_key)
btree->huffman_value = NULL;
__wt_huffman_close(session, btree->huffman_key);
btree->huffman_key = NULL;
}
if (btree->huffman_value != NULL) {
__wt_huffman_close(session, btree->huffman_value);
btree->huffman_value = NULL;
}
}
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