xdiff/xhistogram.c - jrn/git - Git at Google

 /*
  * Copyright (C) 2010, Google Inc.
  * and other copyright owners as documented in JGit's IP log.
  *
  * This program and the accompanying materials are made available
  * under the terms of the Eclipse Distribution License v1.0 which
  * accompanies this distribution, is reproduced below, and is
  * available at http://www.eclipse.org/org/documents/edl-v10.php
  *
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or
  * without modification, are permitted provided that the following
  * conditions are met:
  *
  * - Redistributions of source code must retain the above copyright
  *   notice, this list of conditions and the following disclaimer.
  *
  * - Redistributions in binary form must reproduce the above
  *   copyright notice, this list of conditions and the following
  *   disclaimer in the documentation and/or other materials provided
  *   with the distribution.
  *
  * - Neither the name of the Eclipse Foundation, Inc. nor the
  *   names of its contributors may be used to endorse or promote
  *   products derived from this software without specific prior
  *   written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
  * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "xinclude.h"
 #include "xtypes.h"
 #include "xdiff.h"

 #define MAX_PTR	UINT_MAX
 #define MAX_CNT	UINT_MAX

 #define LINE_END(n) (line##n + count##n - 1)
 #define LINE_END_PTR(n) (*line##n + *count##n - 1)

 struct histindex {
 	struct record {
 		unsigned int ptr, cnt;
 		struct record *next;
 	} **records, /* an ocurrence */
 	  **line_map; /* map of line to record chain */
 	chastore_t rcha;
 	unsigned int *next_ptrs;
 	unsigned int table_bits,
 		     records_size,
 		     line_map_size;

 	unsigned int max_chain_length,
 		     key_shift,
 		     ptr_shift;

 	unsigned int cnt,
 		     has_common;

 	xdfenv_t *env;
 	xpparam_t const *xpp;
 };

 struct region {
 	unsigned int begin1, end1;
 	unsigned int begin2, end2;
 };

 #define LINE_MAP(i, a) (i->line_map[(a) - i->ptr_shift])

 #define NEXT_PTR(index, ptr) \
 	(index->next_ptrs[(ptr) - index->ptr_shift])

 #define CNT(index, ptr) \
 	((LINE_MAP(index, ptr))->cnt)

 #define REC(env, s, l) \
 	(env->xdf##s.recs[l - 1])

 static int cmp_recs(xpparam_t const *xpp,
 	xrecord_t *r1, xrecord_t *r2)
 {
 	return r1->ha == r2->ha &&
 		xdl_recmatch(r1->ptr, r1->size, r2->ptr, r2->size,
 			    xpp->flags);
 }

 #define CMP_ENV(xpp, env, s1, l1, s2, l2) \
 	(cmp_recs(xpp, REC(env, s1, l1), REC(env, s2, l2)))

 #define CMP(i, s1, l1, s2, l2) \
 	(cmp_recs(i->xpp, REC(i->env, s1, l1), REC(i->env, s2, l2)))

 #define TABLE_HASH(index, side, line) \
 	XDL_HASHLONG((REC(index->env, side, line))->ha, index->table_bits)

 static int scanA(struct histindex *index, int line1, int count1)
 {
 	unsigned int ptr, tbl_idx;
 	unsigned int chain_len;
 	struct record **rec_chain, *rec;

 	for (ptr = LINE_END(1); line1 <= ptr; ptr--) {
 		tbl_idx = TABLE_HASH(index, 1, ptr);
 		rec_chain = index->records + tbl_idx;
 		rec = *rec_chain;

 		chain_len = 0;
 		while (rec) {
 			if (CMP(index, 1, rec->ptr, 1, ptr)) {
 				/*
 				 * ptr is identical to another element. Insert
 				 * it onto the front of the existing element
 				 * chain.
 				 */
 				NEXT_PTR(index, ptr) = rec->ptr;
 				rec->ptr = ptr;
 				/* cap rec->cnt at MAX_CNT */
 				rec->cnt = XDL_MIN(MAX_CNT, rec->cnt + 1);
 				LINE_MAP(index, ptr) = rec;
 				goto continue_scan;
 			}

 			rec = rec->next;
 			chain_len++;
 		}

 		if (chain_len == index->max_chain_length)
 			return -1;

 		/*
 		 * This is the first time we have ever seen this particular
 		 * element in the sequence. Construct a new chain for it.
 		 */
 		if (!(rec = xdl_cha_alloc(&index->rcha)))
 			return -1;
 		rec->ptr = ptr;
 		rec->cnt = 1;
 		rec->next = *rec_chain;
 		*rec_chain = rec;
 		LINE_MAP(index, ptr) = rec;

 continue_scan:
 		; /* no op */
 	}

 	return 0;
 }

 static int try_lcs(struct histindex *index, struct region *lcs, int b_ptr,
 	int line1, int count1, int line2, int count2)
 {
 	unsigned int b_next = b_ptr + 1;
 	struct record *rec = index->records[TABLE_HASH(index, 2, b_ptr)];
 	unsigned int as, ae, bs, be, np, rc;
 	int should_break;

 	for (; rec; rec = rec->next) {
 		if (rec->cnt > index->cnt) {
 			if (!index->has_common)
 				index->has_common = CMP(index, 1, rec->ptr, 2, b_ptr);
 			continue;
 		}

 		as = rec->ptr;
 		if (!CMP(index, 1, as, 2, b_ptr))
 			continue;

 		index->has_common = 1;
 		for (;;) {
 			should_break = 0;
 			np = NEXT_PTR(index, as);
 			bs = b_ptr;
 			ae = as;
 			be = bs;
 			rc = rec->cnt;

 			while (line1 < as && line2 < bs
 				&& CMP(index, 1, as - 1, 2, bs - 1)) {
 				as--;
 				bs--;
 				if (1 < rc)
 					rc = XDL_MIN(rc, CNT(index, as));
 			}
 			while (ae < LINE_END(1) && be < LINE_END(2)
 				&& CMP(index, 1, ae + 1, 2, be + 1)) {
 				ae++;
 				be++;
 				if (1 < rc)
 					rc = XDL_MIN(rc, CNT(index, ae));
 			}

 			if (b_next <= be)
 				b_next = be + 1;
 			if (lcs->end1 - lcs->begin1 < ae - as || rc < index->cnt) {
 				lcs->begin1 = as;
 				lcs->begin2 = bs;
 				lcs->end1 = ae;
 				lcs->end2 = be;
 				index->cnt = rc;
 			}

 			if (np == 0)
 				break;

 			while (np <= ae) {
 				np = NEXT_PTR(index, np);
 				if (np == 0) {
 					should_break = 1;
 					break;
 				}
 			}

 			if (should_break)
 				break;

 			as = np;
 		}
 	}
 	return b_next;
 }

 static int find_lcs(struct histindex *index, struct region *lcs,
 	int line1, int count1, int line2, int count2) {
 	int b_ptr;

 	if (scanA(index, line1, count1))
 		return -1;

 	index->cnt = index->max_chain_length + 1;

 	for (b_ptr = line2; b_ptr <= LINE_END(2); )
 		b_ptr = try_lcs(index, lcs, b_ptr, line1, count1, line2, count2);

 	return index->has_common && index->max_chain_length < index->cnt;
 }

 static int fall_back_to_classic_diff(struct histindex *index,
 		int line1, int count1, int line2, int count2)
 {
 	xpparam_t xpp;
 	xpp.flags = index->xpp->flags & ~XDF_DIFF_ALGORITHM_MASK;

 	return xdl_fall_back_diff(index->env, &xpp,
 				  line1, count1, line2, count2);
 }

 static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env,
 	int line1, int count1, int line2, int count2)
 {
 	struct histindex index;
 	struct region lcs;
 	int sz;
 	int result = -1;

 	if (count1 <= 0 && count2 <= 0)
 		return 0;

 	if (LINE_END(1) >= MAX_PTR)
 		return -1;

 	if (!count1) {
 		while(count2--)
 			env->xdf2.rchg[line2++ - 1] = 1;
 		return 0;
 	} else if (!count2) {
 		while(count1--)
 			env->xdf1.rchg[line1++ - 1] = 1;
 		return 0;
 	}

 	memset(&index, 0, sizeof(index));

 	index.env = env;
 	index.xpp = xpp;

 	index.records = NULL;
 	index.line_map = NULL;
 	/* in case of early xdl_cha_free() */
 	index.rcha.head = NULL;

 	index.table_bits = xdl_hashbits(count1);
 	sz = index.records_size = 1 << index.table_bits;
 	sz *= sizeof(struct record *);
 	if (!(index.records = (struct record **) xdl_malloc(sz)))
 		goto cleanup;
 	memset(index.records, 0, sz);

 	sz = index.line_map_size = count1;
 	sz *= sizeof(struct record *);
 	if (!(index.line_map = (struct record **) xdl_malloc(sz)))
 		goto cleanup;
 	memset(index.line_map, 0, sz);

 	sz = index.line_map_size;
 	sz *= sizeof(unsigned int);
 	if (!(index.next_ptrs = (unsigned int *) xdl_malloc(sz)))
 		goto cleanup;
 	memset(index.next_ptrs, 0, sz);

 	/* lines / 4 + 1 comes from xprepare.c:xdl_prepare_ctx() */
 	if (xdl_cha_init(&index.rcha, sizeof(struct record), count1 / 4 + 1) < 0)
 		goto cleanup;

 	index.ptr_shift = line1;
 	index.max_chain_length = 64;

 	memset(&lcs, 0, sizeof(lcs));
 	if (find_lcs(&index, &lcs, line1, count1, line2, count2))
 		result = fall_back_to_classic_diff(&index, line1, count1, line2, count2);
 	else {
 		if (lcs.begin1 == 0 && lcs.begin2 == 0) {
 			while (count1--)
 				env->xdf1.rchg[line1++ - 1] = 1;
 			while (count2--)
 				env->xdf2.rchg[line2++ - 1] = 1;
 			result = 0;
 		} else {
 			result = histogram_diff(xpp, env,
 						line1, lcs.begin1 - line1,
 						line2, lcs.begin2 - line2);
 			if (result)
 				goto cleanup;
 			result = histogram_diff(xpp, env,
 						lcs.end1 + 1, LINE_END(1) - lcs.end1,
 						lcs.end2 + 1, LINE_END(2) - lcs.end2);
 			if (result)
 				goto cleanup;
 		}
 	}

 cleanup:
 	xdl_free(index.records);
 	xdl_free(index.line_map);
 	xdl_free(index.next_ptrs);
 	xdl_cha_free(&index.rcha);

 	return result;
 }

 int xdl_do_histogram_diff(mmfile_t *file1, mmfile_t *file2,
 	xpparam_t const *xpp, xdfenv_t *env)
 {
 	if (xdl_prepare_env(file1, file2, xpp, env) < 0)
 		return -1;

 	return histogram_diff(xpp, env,
 		env->xdf1.dstart + 1, env->xdf1.dend - env->xdf1.dstart + 1,
 		env->xdf2.dstart + 1, env->xdf2.dend - env->xdf2.dstart + 1);
 }
	/*
	* Copyright (C) 2010, Google Inc.
	* and other copyright owners as documented in JGit's IP log.
	*
	* This program and the accompanying materials are made available
	* under the terms of the Eclipse Distribution License v1.0 which
	* accompanies this distribution, is reproduced below, and is
	* available at http://www.eclipse.org/org/documents/edl-v10.php
	*
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or
	* without modification, are permitted provided that the following
	* conditions are met:
	*
	* - Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	*
	* - Redistributions in binary form must reproduce the above
	* copyright notice, this list of conditions and the following
	* disclaimer in the documentation and/or other materials provided
	* with the distribution.
	*
	* - Neither the name of the Eclipse Foundation, Inc. nor the
	* names of its contributors may be used to endorse or promote
	* products derived from this software without specific prior
	* written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
	* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
	* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
	* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
	* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
	* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
	* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
	* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "xinclude.h"
	#include "xtypes.h"
	#include "xdiff.h"

	#define MAX_PTR UINT_MAX
	#define MAX_CNT UINT_MAX

	#define LINE_END(n) (line##n + count##n - 1)
	#define LINE_END_PTR(n) (line##n + count##n - 1)

	struct histindex {
	struct record {
	unsigned int ptr, cnt;
	struct record *next;
	} *records, / an ocurrence */
	*line_map; / map of line to record chain */
	chastore_t rcha;
	unsigned int *next_ptrs;
	unsigned int table_bits,
	records_size,
	line_map_size;

	unsigned int max_chain_length,
	key_shift,
	ptr_shift;

	unsigned int cnt,
	has_common;

	xdfenv_t *env;
	xpparam_t const *xpp;
	};

	struct region {
	unsigned int begin1, end1;
	unsigned int begin2, end2;
	};

	#define LINE_MAP(i, a) (i->line_map[(a) - i->ptr_shift])

	#define NEXT_PTR(index, ptr) \
	(index->next_ptrs[(ptr) - index->ptr_shift])

	#define CNT(index, ptr) \
	((LINE_MAP(index, ptr))->cnt)

	#define REC(env, s, l) \
	(env->xdf##s.recs[l - 1])

	static int cmp_recs(xpparam_t const *xpp,
	xrecord_t r1, xrecord_t r2)
	{
	return r1->ha == r2->ha &&
	xdl_recmatch(r1->ptr, r1->size, r2->ptr, r2->size,
	xpp->flags);
	}

	#define CMP_ENV(xpp, env, s1, l1, s2, l2) \
	(cmp_recs(xpp, REC(env, s1, l1), REC(env, s2, l2)))

	#define CMP(i, s1, l1, s2, l2) \
	(cmp_recs(i->xpp, REC(i->env, s1, l1), REC(i->env, s2, l2)))

	#define TABLE_HASH(index, side, line) \
	XDL_HASHLONG((REC(index->env, side, line))->ha, index->table_bits)

	static int scanA(struct histindex *index, int line1, int count1)
	{
	unsigned int ptr, tbl_idx;
	unsigned int chain_len;
	struct record *rec_chain, rec;

	for (ptr = LINE_END(1); line1 <= ptr; ptr--) {
	tbl_idx = TABLE_HASH(index, 1, ptr);
	rec_chain = index->records + tbl_idx;
	rec = *rec_chain;

	chain_len = 0;
	while (rec) {
	if (CMP(index, 1, rec->ptr, 1, ptr)) {
	/*
	* ptr is identical to another element. Insert
	* it onto the front of the existing element
	* chain.
	*/
	NEXT_PTR(index, ptr) = rec->ptr;
	rec->ptr = ptr;
	/* cap rec->cnt at MAX_CNT */
	rec->cnt = XDL_MIN(MAX_CNT, rec->cnt + 1);
	LINE_MAP(index, ptr) = rec;
	goto continue_scan;
	}

	rec = rec->next;
	chain_len++;
	}

	if (chain_len == index->max_chain_length)
	return -1;

	/*
	* This is the first time we have ever seen this particular
	* element in the sequence. Construct a new chain for it.
	*/
	if (!(rec = xdl_cha_alloc(&index->rcha)))
	return -1;
	rec->ptr = ptr;
	rec->cnt = 1;
	rec->next = *rec_chain;
	*rec_chain = rec;
	LINE_MAP(index, ptr) = rec;

	continue_scan:
	; /* no op */
	}

	return 0;
	}

	static int try_lcs(struct histindex index, struct region lcs, int b_ptr,
	int line1, int count1, int line2, int count2)
	{
	unsigned int b_next = b_ptr + 1;
	struct record *rec = index->records[TABLE_HASH(index, 2, b_ptr)];
	unsigned int as, ae, bs, be, np, rc;
	int should_break;

	for (; rec; rec = rec->next) {
	if (rec->cnt > index->cnt) {
	if (!index->has_common)
	index->has_common = CMP(index, 1, rec->ptr, 2, b_ptr);
	continue;
	}

	as = rec->ptr;
	if (!CMP(index, 1, as, 2, b_ptr))
	continue;

	index->has_common = 1;
	for (;;) {
	should_break = 0;
	np = NEXT_PTR(index, as);
	bs = b_ptr;
	ae = as;
	be = bs;
	rc = rec->cnt;

	while (line1 < as && line2 < bs
	&& CMP(index, 1, as - 1, 2, bs - 1)) {
	as--;
	bs--;
	if (1 < rc)
	rc = XDL_MIN(rc, CNT(index, as));
	}
	while (ae < LINE_END(1) && be < LINE_END(2)
	&& CMP(index, 1, ae + 1, 2, be + 1)) {
	ae++;
	be++;
	if (1 < rc)
	rc = XDL_MIN(rc, CNT(index, ae));
	}

	if (b_next <= be)
	b_next = be + 1;
	if (lcs->end1 - lcs->begin1 < ae - as \|\| rc < index->cnt) {
	lcs->begin1 = as;
	lcs->begin2 = bs;
	lcs->end1 = ae;
	lcs->end2 = be;
	index->cnt = rc;
	}

	if (np == 0)
	break;

	while (np <= ae) {
	np = NEXT_PTR(index, np);
	if (np == 0) {
	should_break = 1;
	break;
	}
	}

	if (should_break)
	break;

	as = np;
	}
	}
	return b_next;
	}

	static int find_lcs(struct histindex index, struct region lcs,
	int line1, int count1, int line2, int count2) {
	int b_ptr;

	if (scanA(index, line1, count1))
	return -1;

	index->cnt = index->max_chain_length + 1;

	for (b_ptr = line2; b_ptr <= LINE_END(2); )
	b_ptr = try_lcs(index, lcs, b_ptr, line1, count1, line2, count2);

	return index->has_common && index->max_chain_length < index->cnt;
	}

	static int fall_back_to_classic_diff(struct histindex *index,
	int line1, int count1, int line2, int count2)
	{
	xpparam_t xpp;
	xpp.flags = index->xpp->flags & ~XDF_DIFF_ALGORITHM_MASK;

	return xdl_fall_back_diff(index->env, &xpp,
	line1, count1, line2, count2);
	}

	static int histogram_diff(xpparam_t const xpp, xdfenv_t env,
	int line1, int count1, int line2, int count2)
	{
	struct histindex index;
	struct region lcs;
	int sz;
	int result = -1;

	if (count1 <= 0 && count2 <= 0)
	return 0;

	if (LINE_END(1) >= MAX_PTR)
	return -1;

	if (!count1) {
	while(count2--)
	env->xdf2.rchg[line2++ - 1] = 1;
	return 0;
	} else if (!count2) {
	while(count1--)
	env->xdf1.rchg[line1++ - 1] = 1;
	return 0;
	}

	memset(&index, 0, sizeof(index));

	index.env = env;
	index.xpp = xpp;

	index.records = NULL;
	index.line_map = NULL;
	/* in case of early xdl_cha_free() */
	index.rcha.head = NULL;

	index.table_bits = xdl_hashbits(count1);
	sz = index.records_size = 1 << index.table_bits;
	sz = sizeof(struct record );
	if (!(index.records = (struct record **) xdl_malloc(sz)))
	goto cleanup;
	memset(index.records, 0, sz);

	sz = index.line_map_size = count1;
	sz = sizeof(struct record );
	if (!(index.line_map = (struct record **) xdl_malloc(sz)))
	goto cleanup;
	memset(index.line_map, 0, sz);

	sz = index.line_map_size;
	sz *= sizeof(unsigned int);
	if (!(index.next_ptrs = (unsigned int *) xdl_malloc(sz)))
	goto cleanup;
	memset(index.next_ptrs, 0, sz);

	/* lines / 4 + 1 comes from xprepare.c:xdl_prepare_ctx() */
	if (xdl_cha_init(&index.rcha, sizeof(struct record), count1 / 4 + 1) < 0)
	goto cleanup;

	index.ptr_shift = line1;
	index.max_chain_length = 64;

	memset(&lcs, 0, sizeof(lcs));
	if (find_lcs(&index, &lcs, line1, count1, line2, count2))
	result = fall_back_to_classic_diff(&index, line1, count1, line2, count2);
	else {
	if (lcs.begin1 == 0 && lcs.begin2 == 0) {
	while (count1--)
	env->xdf1.rchg[line1++ - 1] = 1;
	while (count2--)
	env->xdf2.rchg[line2++ - 1] = 1;
	result = 0;
	} else {
	result = histogram_diff(xpp, env,
	line1, lcs.begin1 - line1,
	line2, lcs.begin2 - line2);
	if (result)
	goto cleanup;
	result = histogram_diff(xpp, env,
	lcs.end1 + 1, LINE_END(1) - lcs.end1,
	lcs.end2 + 1, LINE_END(2) - lcs.end2);
	if (result)
	goto cleanup;
	}
	}

	cleanup:
	xdl_free(index.records);
	xdl_free(index.line_map);
	xdl_free(index.next_ptrs);
	xdl_cha_free(&index.rcha);

	return result;
	}

	int xdl_do_histogram_diff(mmfile_t file1, mmfile_t file2,
	xpparam_t const xpp, xdfenv_t env)
	{
	if (xdl_prepare_env(file1, file2, xpp, env) < 0)
	return -1;

	return histogram_diff(xpp, env,
	env->xdf1.dstart + 1, env->xdf1.dend - env->xdf1.dstart + 1,
	env->xdf2.dstart + 1, env->xdf2.dend - env->xdf2.dstart + 1);
	}