[4/5] Add option for hardlinkable cache of extracted blobs

From

Daniel Barkalow <barkalow@iabervon.org>

Date

Apr 17, 2005, 15:35 UTC

Message-ID

<Pine.LNX.4.21.0504171131230.30848-100000@iabervon.org>

In-Reply-To

<Pine.LNX.4.21.0504171108060.30848-100000@iabervon.org>

Signed-Off-By: Daniel Barkalow <barkalow@iabervon.org>

Index: Makefile
===================================================================
--- 157b46ce1d82b3579e2e1258927b0d9bdbc033ab/Makefile  (mode:100644 sha1:940ef8578cf469354002cd8feaec25d907015267)
+++ 08f7700831e056ad710af69f91e3a8a705b6b2b1/Makefile  (mode:100644 sha1:a60fa46404c0487158d232bd021e4798bc8df8de)
@@ -2,6 +2,9 @@
 # 1461501637330902918203684832716283019655932542976 hashes do not give you
 # enough guarantees about no collisions between objects ever hapenning.
 #
+# -DUSE_HARDLINK_CACHE if you want a cache of files to be hardlinked
+# to for unmodified checked out files.
+#
 # -DNSEC if you want git to care about sub-second file mtimes and ctimes.
 # Note that you need some new glibc (at least >2.2.4) for this, and it will
 # BREAK YOUR LOCAL DIFFS! show-diff and anything using it will likely randomly
Index: checkout-cache.c
===================================================================
--- 157b46ce1d82b3579e2e1258927b0d9bdbc033ab/checkout-cache.c  (mode:100644 sha1:5d3028df0a45329e45fff2006719c9267adeb946)
+++ 08f7700831e056ad710af69f91e3a8a705b6b2b1/checkout-cache.c  (mode:100644 sha1:338588259e17dd235fdc7db759d770004a760e15)
@@ -34,6 +34,10 @@
  */
 #include "cache.h"
 
+#ifdef USE_HARDLINK_CACHE
+#define HARDLINK_CACHE ".git/blobs"
+#endif /* USE_HARDLINK_CACHE */
+
 static int force = 0, quiet = 0;
 
 static void create_directories(const char *path)
@@ -67,6 +71,80 @@
 	return fd;
 }
 
+#ifdef HARDLINK_CACHE
+
+/*
+ * NOTE! This returns a statically allocated buffer, so you have to be
+ * careful about using it. Do a "strdup()" if you need to save the
+ * filename.
+ */
+char *sha1_blob_cache_file_name(const unsigned char *sha1)
+{
+	int i;
+	static char *name, *base;
+
+	if (!base) {
+		char *sha1_file_directory = HARDLINK_CACHE;
+		int len = strlen(sha1_file_directory);
+		base = malloc(len + 60);
+		memcpy(base, sha1_file_directory, len);
+		memset(base+len, 0, 60);
+		base[len] = '/';
+		base[len+3] = '/';
+		name = base + len + 1;
+	}
+	for (i = 0; i < 20; i++) {
+		static char hex[] = "0123456789abcdef";
+		unsigned int val = sha1[i];
+		char *pos = name + i*2 + (i > 0);
+		*pos++ = hex[val >> 4];
+		*pos = hex[val & 0xf];
+	}
+	return base;
+}
+
+static int write_entry(struct cache_entry *ce)
+{
+	int fd;
+	void *new;
+	unsigned long size;
+	long wrote;
+	char type[20];
+	char *cache_name;
+	struct stat st;
+
+	cache_name = sha1_blob_cache_file_name(ce->sha1);
+
+	if (stat(cache_name, &st)) {
+		new = read_sha1_file(ce->sha1, type, &size);
+		if (!new || strcmp(type, "blob")) {
+			return error("checkout-cache: unable to read sha1 file of %s (%s)",
+				     ce->name, sha1_to_hex(ce->sha1));
+		}
+		fd = create_file(cache_name, ntohl(ce->ce_mode));
+		if (fd < 0) {
+			free(new);
+			return error("checkout-cache: unable to create %s (%s)",
+				     ce->name, strerror(errno));
+		}
+		wrote = write(fd, new, size);
+		close(fd);
+		free(new);
+		if (wrote != size)
+			return error("checkout-cache: unable to write %s", 
+				     ce->name);
+	}
+	if (link(cache_name, ce->name)) {
+		if (errno == ENOENT) {
+			create_directories(ce->name);
+			link(cache_name, ce->name);
+		}
+	}
+	return 0;
+}
+
+#else
+
 static int write_entry(struct cache_entry *ce)
 {
 	int fd;
@@ -94,6 +172,8 @@
 	return 0;
 }
 
+#endif
+
 static int checkout_entry(struct cache_entry *ce)
 {
 	struct stat st;