Avoid unnecessary copy of object file on cache miss

As noted by Chiaki Ishikawa, ccache performs an unnecessary copy of the
object file from the cache on a cache miss. This was an refactoring
oversight in 18a645451194becb832bd1ff4fee1c1e9f3d0dc5.

diff --git a/NEWS.txt b/NEWS.txt
index b65db96709da2e583d884b960230ca110a2c46ce..c8d5088a7c6d0cd20b798f5be8d03066be5e3617 100644 (file)
--- a/NEWS.txt
+++ b/NEWS.txt
@@ -18,6 +18,8 @@ Bug fixes
 
 - Fixed a bug where ccache deleted clang diagnostics after compiler failures.
 
+- Avoid performing an unnecessary copy of the object file on a cache miss.
+
 
 ccache 3.2.1
 ------------

diff --git a/ccache.c b/ccache.c
index 721c0984340a08496c04e60a6e32d5334d68a89e..cd5ed65d6476ac2069cbc8e4e7e87400e4e62835 100644 (file)
--- a/ccache.c
+++ b/ccache.c
@@ -188,8 +188,7 @@ unsigned lock_staleness_limit = 2000000;
 
 enum fromcache_call_mode {
        FROMCACHE_DIRECT_MODE,
-       FROMCACHE_CPP_MODE,
-       FROMCACHE_COMPILED_MODE
+       FROMCACHE_CPP_MODE
 };
 
 struct pending_tmp_file {
@@ -730,6 +729,43 @@ get_file_from_cache(const char *source, const char *dest)
        cc_log("Created from cache: %s -> %s", source, dest);
 }
 
+/* Send cached stderr, if any, to stderr. */
+static void
+send_cached_stderr(void)
+{
+       int fd_stderr = open(cached_stderr, O_RDONLY | O_BINARY);
+       if (fd_stderr != -1) {
+               copy_fd(fd_stderr, 2);
+               close(fd_stderr);
+       }
+}
+
+/* Create or update the manifest file. */
+void update_manifest_file(void)
+{
+       struct stat st;
+       size_t old_size = 0; /* in bytes */
+
+       if (!conf->direct_mode
+           || !included_files
+           || conf->read_only
+           || conf->read_only_direct) {
+               return;
+       }
+
+       if (stat(manifest_path, &st) == 0) {
+               old_size = file_size(&st);
+       }
+       if (manifest_put(manifest_path, cached_obj_hash, included_files)) {
+               cc_log("Added object file hash to %s", manifest_path);
+               update_mtime(manifest_path);
+               stat(manifest_path, &st);
+               stats_update_size(file_size(&st) - old_size, old_size == 0 ? 1 : 0);
+       } else {
+               cc_log("Failed to add object file hash to %s", manifest_path);
+       }
+}
+
 /* run the real compiler and put the result in cache */
 static void
 to_cache(struct args *args)
@@ -895,6 +931,9 @@ to_cache(struct args *args)
        }
 
        put_file_in_cache(output_obj, cached_obj);
+       if (generating_dependencies) {
+               put_file_in_cache(output_dep, cached_dep);
+       }
        stats_update(STATS_TOCACHE);
 
        /* Make sure we have a CACHEDIR.TAG in the cache part of cache_dir. This can
@@ -920,6 +959,10 @@ to_cache(struct args *args)
                }
        }
 
+       /* Everything OK. */
+       send_cached_stderr();
+       update_manifest_file();
+
        free(tmp_stderr);
        free(tmp_stdout);
 }
@@ -1419,12 +1462,11 @@ calculate_object_hash(struct args *args, struct mdfour *hash, int direct_mode)
 static void
 from_cache(enum fromcache_call_mode mode, bool put_object_in_manifest)
 {
-       int fd_stderr;
        struct stat st;
-       bool produce_dep_file;
+       bool produce_dep_file = false;
 
        /* the user might be disabling cache hits */
-       if (mode != FROMCACHE_COMPILED_MODE && conf->recache) {
+       if (conf->recache) {
                return;
        }
 
@@ -1442,7 +1484,7 @@ from_cache(enum fromcache_call_mode mode, bool put_object_in_manifest)
 
        /*
         * Occasionally, e.g. on hard reset, our cache ends up as just filesystem
-        * meta-data with no content catch an easy case of this.
+        * meta-data with no content. Catch an easy case of this.
         */
        if (st.st_size == 0) {
                cc_log("Invalid (empty) object file %s in cache", cached_obj);
@@ -1483,36 +1525,14 @@ from_cache(enum fromcache_call_mode mode, bool put_object_in_manifest)
                update_mtime(cached_dia);
        }
 
-       if (generating_dependencies && mode != FROMCACHE_DIRECT_MODE) {
+       if (generating_dependencies && mode == FROMCACHE_CPP_MODE) {
                put_file_in_cache(output_dep, cached_dep);
        }
 
-       /* Send the stderr, if any. */
-       fd_stderr = open(cached_stderr, O_RDONLY | O_BINARY);
-       if (fd_stderr != -1) {
-               copy_fd(fd_stderr, 2);
-               close(fd_stderr);
-       }
+  send_cached_stderr();
 
-       /* Create or update the manifest file. */
-       if (conf->direct_mode
-           && put_object_in_manifest
-           && included_files
-           && !conf->read_only
-           && !conf->read_only_direct) {
-               struct stat st;
-               size_t old_size = 0; /* in bytes */
-               if (stat(manifest_path, &st) == 0) {
-                       old_size = file_size(&st);
-               }
-               if (manifest_put(manifest_path, cached_obj_hash, included_files)) {
-                       cc_log("Added object file hash to %s", manifest_path);
-                       update_mtime(manifest_path);
-                       stat(manifest_path, &st);
-                       stats_update_size(file_size(&st) - old_size, old_size == 0 ? 1 : 0);
-               } else {
-                       cc_log("Failed to add object file hash to %s", manifest_path);
-               }
+       if (put_object_in_manifest) {
+               update_manifest_file();
        }
 
        /* log the cache hit */
@@ -1526,10 +1546,6 @@ from_cache(enum fromcache_call_mode mode, bool put_object_in_manifest)
                cc_log("Succeeded getting cached result");
                stats_update(STATS_CACHEHIT_CPP);
                break;
-
-       case FROMCACHE_COMPILED_MODE:
-               /* Stats already updated in to_cache(). */
-               break;
        }
 
        /* and exit with the right status code */
@@ -2706,13 +2722,7 @@ ccache(int argc, char *argv[])
        /* run real compiler, sending output to cache */
        to_cache(compiler_args);
 
-       /* return from cache */
-       from_cache(FROMCACHE_COMPILED_MODE, put_object_in_manifest);
-
-       /* oh oh! */
-       cc_log("Secondary from_cache failed");
-       stats_update(STATS_ERROR);
-       failed();
+       exit(0);
 }
 
 static void