read-cache: tweak racy-git delay logic

Instead of looping over the entries and writing out, use a
separate loop after all entries have been written out to check
how many entries are racily clean.  Make sure that the newly
created index file gets the right timestamp when we check by
flushing the buffered data by ce_write().

Signed-off-by: Junio C Hamano <junkio@cox.net>

read-cache.c

@@ -841,6 +841,18 @@ int read_cache_from(const char *path)
 static unsigned char write_buffer[WRITE_BUFFER_SIZE];
 static unsigned long write_buffer_len;
 
+static int ce_write_flush(SHA_CTX *context, int fd)
+{
+	unsigned int buffered = write_buffer_len;
+	if (buffered) {
+		SHA1_Update(context, write_buffer, buffered);
+		if (write(fd, write_buffer, buffered) != buffered)
+			return -1;
+		write_buffer_len = 0;
+	}
+	return 0;
+}
+
 static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len)
 {
 	while (len) {
@@ -851,8 +863,8 @@ static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len)
 		memcpy(write_buffer + buffered, data, partial);
 		buffered += partial;
 		if (buffered == WRITE_BUFFER_SIZE) {
-			SHA1_Update(context, write_buffer, WRITE_BUFFER_SIZE);
-			if (write(fd, write_buffer, WRITE_BUFFER_SIZE) != WRITE_BUFFER_SIZE)
+			write_buffer_len = buffered;
+			if (ce_write_flush(context, fd))
 				return -1;
 			buffered = 0;
 		}
@@ -962,19 +974,15 @@ int write_cache(int newfd, struct cache_entry **cache, int entries)
 	if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
 		return -1;
 
-	now = fstat(newfd, &st) ? 0 : st.st_mtime;
-	recent = 0;
 	for (i = 0; i < entries; i++) {
 		struct cache_entry *ce = cache[i];
-		time_t entry_time = (time_t) ntohl(ce->ce_mtime.sec);
 		if (!ce->ce_mode)
 			continue;
-		if (index_file_timestamp && index_file_timestamp <= entry_time)
+		if (index_file_timestamp &&
+		    index_file_timestamp <= ntohl(ce->ce_mtime.sec))
 			ce_smudge_racily_clean_entry(ce);
 		if (ce_write(&c, newfd, ce, ce_size(ce)) < 0)
 			return -1;
-		if (now && now <= entry_time)
-			recent++;
 	}
 
 	/* Write extension data here */
@@ -1004,19 +1012,42 @@ int write_cache(int newfd, struct cache_entry **cache, int entries)
 	 * This assumes that nobody is touching the working tree while
 	 * we are updating the index.
 	 */
-	if (20 < recent || entries <= recent * 4) {
-		now = fstat(newfd, &st) ? 0 : st.st_mtime;
-		while (now && !fstat(newfd, &st) && st.st_mtime <= now) {
-			struct timespec rq, rm;
-			off_t where = lseek(newfd, 0, SEEK_CUR);
-			rq.tv_sec = 0;
-			rq.tv_nsec = 250000000;
-			nanosleep(&rq, &rm);
-			if ((where == (off_t) -1) ||
-			    (write(newfd, "", 1) != 1) ||
-			    (lseek(newfd, -1, SEEK_CUR) != where) ||
-			    ftruncate(newfd, where))
-				break;
+
+	/* Make sure that the new index file has st_mtime
+	 * that is current enough -- ce_write() batches the data
+	 * so it might not have written anything yet.
+	 */
+	ce_write_flush(&c, newfd);
+
+	now = fstat(newfd, &st) ? 0 : st.st_mtime;
+	if (now) {
+		recent = 0;
+		for (i = 0; i < entries; i++) {
+			struct cache_entry *ce = cache[i];
+			time_t entry_time = (time_t) ntohl(ce->ce_mtime.sec);
+			if (!ce->ce_mode)
+				continue;
+			if (now && now <= entry_time)
+				recent++;
+		}
+		if (20 < recent && entries <= recent * 4) {
+#if 0
+			fprintf(stderr, "entries    %d\n", entries);
+			fprintf(stderr, "recent     %d\n", recent);
+			fprintf(stderr, "now        %lu\n", now);
+#endif
+			while (!fstat(newfd, &st) && st.st_mtime <= now) {
+				struct timespec rq, rm;
+				off_t where = lseek(newfd, 0, SEEK_CUR);
+				rq.tv_sec = 0;
+				rq.tv_nsec = 250000000;
+				nanosleep(&rq, &rm);
+				if ((where == (off_t) -1) ||
+				    (write(newfd, "", 1) != 1) ||
+				    (lseek(newfd, -1, SEEK_CUR) != where) ||
+				    ftruncate(newfd, where))
+					break;
+			}
 		}
 	}
 	return ce_flush(&c, newfd);