From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from [87.239.111.99] (localhost [127.0.0.1]) by dev.tarantool.org (Postfix) with ESMTP id F18796F852; Sun, 14 Nov 2021 12:13:17 +0300 (MSK) DKIM-Filter: OpenDKIM Filter v2.11.0 dev.tarantool.org F18796F852 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=tarantool.org; s=dev; t=1636881198; bh=bELd3otZufau5Hu0+jzJe/ypsuB7SK9GZGUK5cRJuuY=; h=To:Cc:Date:Subject:List-Id:List-Unsubscribe:List-Archive: List-Post:List-Help:List-Subscribe:From:Reply-To:From; b=iRaDza6ohalRA+EQxv8xozEH9ekhfpVJFPqeIC3yMXFkg4yd8smgQWXRABON3vFgN I42HbBYOh2EigOhf+uZFkeOIIrSIkV/lyGlCdL2sOeCoooWhZVa8sGBu/4t/Jt38xn 1Vrp3j5GttT87vybFuKFjqK17mj3i/NO88MEeIXw= Received: from mail-lj1-f173.google.com (mail-lj1-f173.google.com [209.85.208.173]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by dev.tarantool.org (Postfix) with ESMTPS id 0C5276F852 for ; Sun, 14 Nov 2021 12:13:15 +0300 (MSK) DKIM-Filter: OpenDKIM Filter v2.11.0 dev.tarantool.org 0C5276F852 Received: by mail-lj1-f173.google.com with SMTP id v15so28410400ljc.0 for ; Sun, 14 Nov 2021 01:13:14 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=0/fhyGj6cMTdPET+mL5LGDk2yT7du4ru6Ay0FbE2V24=; b=jUof9BfYKW1weaRWaOZR+Kxa9cTKb2X6yhD9XAOgEu6wfLBRkwnYR0opfg1E5iYNlB YXL515k+bY8uRbM7bl28MeRMLH/NqYbjRm4gjDnNPxBr96EhKQH7wBY5wEq5tMwLCs+0 7+Wolc0GK7qa4UI0bphiD0FGDGJX6YbVmDerbFzsoTgBo3DGxMpt7gFya3A/890TP7BQ 1oOKfUNk+qbZEOD+MhcqnhYyBRTbQxMzAi4F70d7Gin3Rn1eiC6TpfWaFDHj9tXq0TaL XKXn7/YZlrERs8sVNIYmv2raN4yZK3SF1j3sAidQcOngOv1QK3e8Mq3ET/9m0z6tY2he QvPw== X-Gm-Message-State: AOAM531a/aqnz85Htf2JsU27Ux3DD/ZnFRx+8S+cEo5euQHnMIwtrzhx vpBPW7vAS+m+/DLBeTwd/0gX3lczzw7MKw== X-Google-Smtp-Source: ABdhPJzm7pCMR+5kDt7nu5cQDokL9qcW3YqwOU1HrxoGOWVjnrTAEQ46rRHfzmq6nXEu0XupOikOtA== X-Received: by 2002:a2e:97cb:: with SMTP id m11mr29379737ljj.324.1636881194000; Sun, 14 Nov 2021 01:13:14 -0800 (PST) Received: from localhost.localdomain ([109.252.85.87]) by smtp.gmail.com with ESMTPSA id p8sm1101970ljh.76.2021.11.14.01.13.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 14 Nov 2021 01:13:13 -0800 (PST) X-Google-Original-From: Lord To: tarantool-patches@dev.tarantool.org Cc: Gleb Date: Sun, 14 Nov 2021 12:13:10 +0300 Message-Id: <20211114091310.4147-1-lord.nemo@protonmail.com> X-Mailer: git-send-email 2.33.1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: [Tarantool-patches] [PATCH] sql: Replace naive position alg with KMP X-BeenThere: tarantool-patches@dev.tarantool.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Tarantool development patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Lord via Tarantool-patches Reply-To: Lord Errors-To: tarantool-patches-bounces@dev.tarantool.org Sender: "Tarantool-patches" From: Gleb Replaces positioning logic in POSITION() and REPLACE() SQL functions with Knuth-Morris-Pratt algorithm by adding two different versions of the latter for STRING and VARBINARY arguments and corresponding prefix table generators. Improved asymptotics of positioning logic to: time O(haystack_len + needle_len), mem O(needle_len) As one of collating types is a Unicode string, ICU UCharIterators had to be used and thus Unicode letters are compared as UChar32 values and normalization is not done ('a' and 'รค' are treated as different) Closes tarantool/tarantool#6492 --- src/box/sql/func.c | 402 ++++++++++++++++++++++++++------- 1 file changed, 321 insertions(+), 90 deletions(-) diff --git a/src/box/sql/func.c b/src/box/sql/func.c index 29d713fd0..badfbc176 100644 --- a/src/box/sql/func.c +++ b/src/box/sql/func.c @@ -291,6 +291,144 @@ absFunc(sql_context * context, int argc, sql_value ** argv) } } +/** + * Implementation of prefix table generator + * prefix_table_gen() is a part of Knuth-Morris-Pratt algorithm + * that is used in position() and replaceFunc() to find + * instances of `needle` in `haystack` bin data + */ +inline static void +prefix_table_gen_bin(const unsigned char *needle, + const size_t n_needle_bytes, + size_t *table) +{ + size_t i = 1, j = 0; + table[0] = 0; + while (i < n_needle_bytes) { + if (needle[i] != needle[j]) { + if (j == 0) { + table[i] = 0; + ++i; + } else { + j = table[j - 1]; + } + } else { + table[i] = j + 1; + ++i; + ++j; + } + } +} + +/** + * Implementation of prefix table generator using UCharIterators + * prefix_table_gen() is a part of Knuth-Morris-Pratt algorithm + * that is used in position() to find instances of `needle` + * in `haystack` unicode string + */ +inline static void +prefix_table_gen_ustr(const UCharIterator *needle_begin, + const unsigned char *needle_str, + const size_t n_needle_bytes, + const size_t n_needle_chars, + size_t table[]) +{ + table[0] = 0; + UCharIterator needle_iter; + UCharIterator second_iter; + uiter_setUTF8(&needle_iter, needle_str, n_needle_bytes); + uiter_setUTF8(&second_iter, needle_str, n_needle_bytes); + needle_iter.next(&needle_iter); + while (needle_iter.getIndex(&needle_iter, UITER_CURRENT) < n_needle_chars) { + if (needle_iter.current(&needle_iter) != second_iter.current(&second_iter)) { + if (second_iter.getIndex(&second_iter, UITER_CURRENT) == 0) { + table[needle_iter.getIndex(&needle_iter, UITER_CURRENT)] = 0; + needle_iter.next(&needle_iter); + } else { + second_iter.move(&second_iter, table[second_iter.getIndex(&second_iter, UITER_CURRENT) - 1], UITER_START); + } + } else { + table[needle_iter.getIndex(&needle_iter, UITER_CURRENT)] = second_iter.getIndex(&second_iter, UITER_CURRENT) + 1; + needle_iter.next(&needle_iter); + second_iter.next(&second_iter); + } + } +} + +/** + * Implementation of the KMP algorithm to find substring + * in a bin array starting from given position. + * + * Requires index for starting position in `haystack`. + * + * Returns found substring position + 1 or 0 if there is no such substring. + */ +static int +kmp_bin(const unsigned char *haystack_str, + const unsigned char *needle_str, + const size_t n_haystack_bytes, + const size_t n_needle_bytes, + size_t i, + const size_t *prefix_table) +{ + size_t j = 0; + int position = 0; + while (i < n_haystack_bytes) { + if (needle_str[j] == haystack_str[i]) { + ++i; + ++j; + } else { + if (j == 0) + ++i; + else + j = prefix_table[j - 1]; + } + if (j >= n_needle_bytes) { + position = i - j + 1; + return position; + } + } + return position; +} + +/** + * Implementation of the KMP algorithm to find substring + * in an array of unicode chars starting from given iterator. + * + * Requires UCharIterator [haystack_iter] of starting position + * in `haystack`, iterator gets set to the first item after found + * `needle` or reaches the end of haystack if there is no such substring. + * + * Returns found substring position + 1 or 0 if no such substring. + */ +inline static int +kmp_ustr(struct sql_context *context, + UCharIterator *haystack_iter, + UCharIterator *needle_iter, + const size_t n_haystack_chars, + const size_t *prefix_table) +{ + struct coll *coll = sqlGetFuncCollSeq(context); + int position = 0; + while (haystack_iter->getIndex(haystack_iter, UITER_CURRENT) < n_haystack_chars) { + if (needle_iter->current(needle_iter) == haystack_iter->current(haystack_iter)) { + needle_iter->next(needle_iter); + haystack_iter->next(haystack_iter); + } else { + if (needle_iter->getIndex(needle_iter, UITER_CURRENT) == 0) + haystack_iter->next(haystack_iter); + else + needle_iter->move(needle_iter, prefix_table[needle_iter->getIndex(needle_iter, UITER_CURRENT) - 1], UITER_START); + } + if (!needle_iter->hasNext(needle_iter)) { + position = haystack_iter->getIndex(haystack_iter, UITER_CURRENT) - needle_iter->getIndex(needle_iter, UITER_CURRENT) + 1; + haystack_iter->next(haystack_iter); + return position; + } + } + return position; +} + /** * Implementation of the position() function. * @@ -339,9 +477,10 @@ position_func(struct sql_context *context, int argc, struct Mem **argv) return; } - int n_needle_bytes = mem_len_unsafe(needle); - int n_haystack_bytes = mem_len_unsafe(haystack); + size_t n_needle_bytes = mem_len_unsafe(needle); + size_t n_haystack_bytes = mem_len_unsafe(haystack); int position = 1; + size_t *prefix_table = NULL; if (n_needle_bytes > 0) { const unsigned char *haystack_str; const unsigned char *needle_str; @@ -351,18 +490,24 @@ position_func(struct sql_context *context, int argc, struct Mem **argv) assert(needle_str != NULL); assert(haystack_str != NULL || n_haystack_bytes == 0); /* - * Naive implementation of substring - * searching: matching time O(n * m). - * Can be improved. + * Basic version of the KMP alg + * searching: matching time O(n + m), requires mem O(m). */ - while (n_needle_bytes <= n_haystack_bytes && - memcmp(haystack_str, needle_str, n_needle_bytes) != 0) { - position++; - n_haystack_bytes--; - haystack_str++; + prefix_table = calloc(n_needle_bytes, sizeof(size_t)); + + if (prefix_table != NULL) { + prefix_table_gen_bin(needle_str, n_needle_bytes, prefix_table); + position = kmp_bin(haystack_str, needle_str, n_haystack_bytes, n_needle_bytes, 0, prefix_table); + } else { + while (n_needle_bytes <= n_haystack_bytes && + memcmp(haystack_str, needle_str, n_needle_bytes) != 0) { + position++; + n_haystack_bytes--; + haystack_str++; + } + if (n_needle_bytes > n_haystack_bytes) + position = 0; } - if (n_needle_bytes > n_haystack_bytes) - position = 0; } else { /* * Code below handles not only simple @@ -376,52 +521,74 @@ position_func(struct sql_context *context, int argc, struct Mem **argv) * needle char size. */ haystack_str = mem_as_ustr(haystack); - needle_str = mem_as_ustr(needle); + needle_str = mem_as_ustr(needle); int n_needle_chars = sql_utf8_char_count(needle_str, n_needle_bytes); int n_haystack_chars = sql_utf8_char_count(haystack_str, - n_haystack_bytes); + n_haystack_bytes); + if (n_haystack_chars < n_needle_chars) { position = 0; goto finish; } - /* - * Comparison window is determined by - * beg_offset and end_offset. beg_offset - * is offset in bytes from haystack - * beginning to window beginning. - * end_offset is offset in bytes from - * haystack beginning to window end. - */ - int end_offset = 0; - for (int c = 0; c < n_needle_chars; c++) { - SQL_UTF8_FWD_1(haystack_str, end_offset, - n_haystack_bytes); - } - int beg_offset = 0; - struct coll *coll = sqlGetFuncCollSeq(context); - int c; - for (c = 0; c + n_needle_chars <= n_haystack_chars; c++) { - if (coll->cmp((const char *) haystack_str + beg_offset, - end_offset - beg_offset, - (const char *) needle_str, - n_needle_bytes, coll) == 0) - goto finish; - position++; - /* Update offsets. */ - SQL_UTF8_FWD_1(haystack_str, beg_offset, - n_haystack_bytes); - SQL_UTF8_FWD_1(haystack_str, end_offset, - n_haystack_bytes); + + prefix_table = calloc(n_needle_chars, sizeof(size_t)); + + if (prefix_table != NULL) { + /* + * KMP algorithm with unicode support + * searching: time O(n + m), mem O(m) + */ + UCharIterator needle_iter, haystack_iter; + + uiter_setUTF8( &needle_iter, needle_str, n_needle_bytes); + uiter_setUTF8(&haystack_iter, haystack_str, n_haystack_bytes); + + prefix_table_gen_ustr(&needle_iter, needle_str, n_needle_bytes, n_needle_chars, prefix_table); + position = kmp_ustr(context, &haystack_iter, &needle_iter, n_haystack_chars, prefix_table); + } else { + /* + * Naive searching substring algorithm + * searching: time O(m * n), mem O(1) + * + * Comparison window is determined by + * beg_offset and end_offset. beg_offset + * is offset in bytes from haystack + * beginning to window beginning. + * end_offset is offset in bytes from + * haystack beginning to window end. + */ + int end_offset = 0; + for (int c = 0; c < n_needle_chars; c++) { + SQL_UTF8_FWD_1(haystack_str, end_offset, + n_haystack_bytes); + } + int beg_offset = 0; + struct coll *coll = sqlGetFuncCollSeq(context); + int c; + for (c = 0; c + n_needle_chars <= n_haystack_chars; c++) { + if (coll->cmp((const char *) haystack_str + beg_offset, + end_offset - beg_offset, + (const char *) needle_str, + n_needle_bytes, coll) == 0) + goto finish; + position++; + /* Update offsets. */ + SQL_UTF8_FWD_1(haystack_str, beg_offset, + n_haystack_bytes); + SQL_UTF8_FWD_1(haystack_str, end_offset, + n_haystack_bytes); + } + /* Needle was not found in the haystack. */ + position = 0; } - /* Needle was not found in the haystack. */ - position = 0; } } finish: + free(prefix_table); assert(position >= 0); sql_result_uint(context, position); } @@ -1280,24 +1447,31 @@ zeroblobFunc(sql_context * context, int argc, sql_value ** argv) } /* - * The replace() function. Three arguments are all strings: call + * The replace() function. Three arguments are all strings: call * them A, B, and C. The result is also a string which is derived * from A by replacing every occurrence of B with C. The match * must be exact. Collating sequences are not used. */ static void -replaceFunc(sql_context * context, int argc, sql_value ** argv) +replaceFunc(sql_context *context, int argc, sql_value **argv) { - const unsigned char *zStr; /* The input string A */ - const unsigned char *zPattern; /* The pattern string B */ - const unsigned char *zRep; /* The replacement string C */ - unsigned char *zOut; /* The output */ - int nStr; /* Size of zStr */ - int nPattern; /* Size of zPattern */ - int nRep; /* Size of zRep */ - i64 nOut; /* Maximum size of zOut */ - int loopLimit; /* Last zStr[] that might match zPattern[] */ - int i, j; /* Loop counters */ + const unsigned char *zStr; /* The input string A */ + const unsigned char *zPattern; /* The pattern string B */ + const unsigned char *zRep; /* The replacement string C */ + unsigned char *zOut; /* The output */ + int nStr; /* Size of zStr */ + int nPattern; /* Size of zPattern */ + int nRep; /* Size of zRep */ + i64 nOut; /* Maximum size of zOut */ + int loopLimit; /* Last zStr[] that might match zPattern[] */ + int i, j; /* Loop counters */ + int nCnt = 0; /* counter for number of Pattern in Str */ + int iStr = 0; /* zStr iterator for finding Patter with KMP */ + int nCopiedOut = 0; /* zOut iterator for already copied mem */ + int nCopiedStr = 0; /* zStr iterator for already copied mem */ + int nPatternPos = 0; /* zStr iterator for found Pattern position */ + size_t *prefix_table = NULL; /* prefix table for kmp alg */ + assert(argc == 3); UNUSED_PARAMETER(argc); @@ -1309,7 +1483,7 @@ replaceFunc(sql_context * context, int argc, sql_value ** argv) zPattern = mem_as_ustr(argv[1]); if (zPattern == 0) { assert(mem_is_null(argv[1]) - || sql_context_db_handle(context)->mallocFailed); + || sql_context_db_handle(context)->mallocFailed); return; } nPattern = mem_len_unsafe(argv[1]); @@ -1331,40 +1505,89 @@ replaceFunc(sql_context * context, int argc, sql_value ** argv) return; } loopLimit = nStr - nPattern; - for (i = j = 0; i <= loopLimit; i++) { - if (zStr[i] != zPattern[0] - || memcmp(&zStr[i], zPattern, nPattern)) { - zOut[j++] = zStr[i]; - } else { - u8 *zOld; - sql *db = sql_context_db_handle(context); - nOut += nRep - nPattern; - testcase(nOut - 1 == db->aLimit[SQL_LIMIT_LENGTH]); - testcase(nOut - 2 == db->aLimit[SQL_LIMIT_LENGTH]); - if (nOut - 1 > db->aLimit[SQL_LIMIT_LENGTH]) { - diag_set(ClientError, ER_SQL_EXECUTE, "string "\ - "or binary string is too big"); - context->is_aborted = true; - sql_free(zOut); - return; - } - zOld = zOut; - zOut = sql_realloc64(zOut, (int)nOut); - if (zOut == 0) { - context->is_aborted = true; - sql_free(zOld); - return; + + if (prefix_table != NULL) { + /* + * optimized replacement logic using the KMP algorithm + * requires additional O(nPattern) memory for prefix table + * replacing: time O(n + m) + */ + + /* precalculating prefix table */ + prefix_table = calloc(nPattern, sizeof(size_t)); + prefix_table_gen_bin(zPattern, nPattern, prefix_table); + /* counting the number of Pattern occurrences */ + for (nCnt = iStr = nPatternPos = 0;;) { + nPatternPos = kmp_bin(zStr, zPattern, nStr, nPattern, iStr, prefix_table); + iStr = nPatternPos + nPattern; + if (nPatternPos == 0) + break; + ++nCnt; + } + /* reallocationg mem for zOut */ + nOut += (nRep - nPattern) * nCnt; + assert(nOut < SQL_MAX_LENGTH); + zOut = contextMalloc(context, (i64) nOut); + if (zOut == 0) { + return; + } + /* coping and replacing in-place */ + for (iStr = nCopiedStr = nCopiedOut = nPatternPos = 0;;) { + nPatternPos = kmp_bin(zStr, zPattern, nStr, nPattern, iStr, prefix_table); + iStr = nPatternPos + nPattern; + if (nPatternPos == 0) + break; + assert(nPatternPos >= nCopiedStr); + memcpy(zOut + nCopiedOut, zStr + nCopiedStr, nPatternPos - nCopiedStr); + nCopiedOut += nPatternPos - nCopiedStr; + memcpy(zOut + nCopiedOut, zRep, nRep); + nCopiedOut += nRep; + nCopiedStr = nPatternPos + nPattern; + } + memcpy(zOut + nCopiedOut, zStr + nCopiedStr, nStr - nCopiedStr); + zOut[nOut - 1] = 0; + free(prefix_table); + } else { + /* + * Naive replacing substring algorithm + * replacing: time O(n * m), mem O(1) + * used if cannot allocate mem for prefix table + */ + for (i = j = 0; i <= loopLimit; i++) { + if (zStr[i] != zPattern[0] + || memcmp(&zStr[i], zPattern, nPattern)) { + zOut[j++] = zStr[i]; + } else { + u8 *zOld; + sql *db = sql_context_db_handle(context); + nOut += nRep - nPattern; + testcase(nOut - 1 == db->aLimit[SQL_LIMIT_LENGTH]); + testcase(nOut - 2 == db->aLimit[SQL_LIMIT_LENGTH]); + if (nOut - 1 > db->aLimit[SQL_LIMIT_LENGTH]) { + diag_set(ClientError, ER_SQL_EXECUTE, "string "\ + "or binary string is too big"); + context->is_aborted = true; + sql_free(zOut); + return; + } + zOld = zOut; + zOut = sql_realloc64(zOut, (int)nOut); + if (zOut == 0) { + context->is_aborted = true; + sql_free(zOld); + return; + } + memcpy(&zOut[j], zRep, nRep); + j += nRep; + i += nPattern - 1; } - memcpy(&zOut[j], zRep, nRep); - j += nRep; - i += nPattern - 1; } + assert(j + nStr - i + 1 == nOut); + memcpy(&zOut[j], &zStr[i], nStr - i); + j += nStr - i; + assert(j <= nOut); + zOut[j] = 0; } - assert(j + nStr - i + 1 == nOut); - memcpy(&zOut[j], &zStr[i], nStr - i); - j += nStr - i; - assert(j <= nOut); - zOut[j] = 0; if (context->func->def->returns == FIELD_TYPE_STRING) mem_set_str_dynamic(context->pOut, (char *)zOut, j); else