/*

 * Copyright (C) 2008 Linus Torvalds

 */

#include "cache.h"

#include "pathspec.h"

#include "dir.h"

#include "fsmonitor.h"

#ifdef NO_PTHREADS

static void preload_index(struct index_state *index,

			  const struct pathspec *pathspec)

{

	; /* nothing */

}

#else

#include <pthread.h>

/*

 * Mostly randomly chosen maximum thread counts: we

 * cap the parallelism to 20 threads, and we want

 * to have at least 500 lstat's per thread for it to

 * be worth starting a thread.

 */

#define MAX_PARALLEL (20)

#define THREAD_COST (500)

struct thread_data {

	pthread_t pthread;

	struct index_state *index;

	struct pathspec pathspec;

	int offset, nr;

};

static void *preload_thread(void *_data)

{

	int nr;

	struct thread_data *p = _data;

	struct index_state *index = p->index;

	struct cache_entry **cep = index->cache + p->offset;

	struct cache_def cache = CACHE_DEF_INIT;

	nr = p->nr;

	if (nr + p->offset > index->cache_nr)

		nr = index->cache_nr - p->offset;

	do {

		struct cache_entry *ce = *cep++;

		struct stat st;

		if (ce_stage(ce))

			continue;

		if (S_ISGITLINK(ce->ce_mode))

			continue;

		if (ce_uptodate(ce))

			continue;

		if (ce_skip_worktree(ce))

			continue;

		if (ce->ce_flags & CE_FSMONITOR_VALID)

			continue;

		if (!ce_path_match(ce, &p->pathspec, NULL))

			continue;

		if (threaded_has_symlink_leading_path(&cache, ce->name, ce_namelen(ce)))

			continue;

		if (lstat(ce->name, &st))

			continue;

		if (ie_match_stat(index, ce, &st, CE_MATCH_RACY_IS_DIRTY|CE_MATCH_IGNORE_FSMONITOR))

			continue;

		ce_mark_uptodate(ce);

		mark_fsmonitor_valid(ce);

	} while (--nr > 0);

	cache_def_clear(&cache);

	return NULL;

}

static void preload_index(struct index_state *index,

			  const struct pathspec *pathspec)

{

	int threads, i, work, offset;

	struct thread_data data[MAX_PARALLEL];

	uint64_t start = getnanotime();

	if (!core_preload_index)

		return;

	threads = index->cache_nr / THREAD_COST;

	if ((index->cache_nr > 1) && (threads < 2) && getenv("GIT_FORCE_PRELOAD_TEST"))

		threads = 2;

	if (threads < 2)

		return;

	if (threads > MAX_PARALLEL)

		threads = MAX_PARALLEL;

	offset = 0;

	work = DIV_ROUND_UP(index->cache_nr, threads);

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

	for (i = 0; i < threads; i++) {

		struct thread_data *p = data+i;

		p->index = index;

		if (pathspec)

			copy_pathspec(&p->pathspec, pathspec);

		p->offset = offset;

		p->nr = work;

		offset += work;

		if (pthread_create(&p->pthread, NULL, preload_thread, p))

			die("unable to create threaded lstat");

	}

	for (i = 0; i < threads; i++) {

		struct thread_data *p = data+i;

		if (pthread_join(p->pthread, NULL))

			die("unable to join threaded lstat");

	}

	trace_performance_since(start, "preload index");

}

#endif

int read_index_preload(struct index_state *index,

		       const struct pathspec *pathspec)

{

	int retval = read_index(index);

	preload_index(index, pathspec);

	return retval;

}