Merge two experimental_local_disk_cache options to one

site/docs/remote-caching.md

@@ -28,6 +28,7 @@ make builds significantly faster.
     * [Delete content from the remote cache](#delete-content-from-the-remote-cache)
 * [Known Issues](#known-issues)
 * [External Links](#external-links)
+* [Build cache](#build-cache)
 * [Bazel remote execution (in development)](#bazel-remote-execution-in-development)
 
 ## Remote caching overview
@@ -306,6 +307,31 @@ You may want to delete content from the cache to:
 * Create a clean cache after a cache was poisoned
 * Reduce the amount of storage used by deleting old outputs
 
+## Build cache
+
+Bazel can use a directory on the filesystem as a remote cache. This is
+useful for sharing build artifacts when switching branches and/or working
+on multiple workspaces of the same project i.e. multiple checkouts. Bazel
+does not garbage collect the directory and thus one might want to set up a
+cron job or similar to periodically clean up the directory. The build cache
+can be enabled with the following flags.
+
+```
+build --build_cache=/path/to/build/cache
+```
+
+Additionally, one can pass a user specific path to the --build_cache flag
+via the ~ character. Bazel will replace this with the current user's home
+directory. This comes in handy when one wants to enable the build cache for
+all developers of a project via the project's checked in `.bazelrc` file.
+
+To have cache hits across different workspaces, additional option should be
+used:
+
+```
+build --experimental_strict_action_env
+```
+
 ## Known issues
 
 **Input file modification during a Build**

src/main/java/com/google/devtools/build/lib/remote/RemoteActionContextProvider.java

@@ -60,7 +60,7 @@ public Iterable<? extends ActionContext> getActionContexts() {
     String buildRequestId = env.getBuildRequestId().toString();
     String commandId = env.getCommandId().toString();
 
-    if (remoteOptions.experimentalRemoteSpawnCache || remoteOptions.experimentalLocalDiskCache) {
+    if (remoteOptions.experimentalRemoteSpawnCache || remoteOptions.buildCache != null) {
       RemoteSpawnCache spawnCache =
           new RemoteSpawnCache(
               env.getExecRoot(),

src/main/java/com/google/devtools/build/lib/remote/RemoteOptions.java

@@ -190,27 +190,18 @@ public final class RemoteOptions extends OptionsBase {
   )
   public boolean experimentalRemoteSpawnCache;
 
-  // TODO(davido): Find a better place for this and the next option.
+  // TODO(davido): Find a better place for this option.
   @Option(
-    name = "experimental_local_disk_cache",
-    defaultValue = "false",
-    category = "remote",
-    documentationCategory = OptionDocumentationCategory.UNCATEGORIZED,
-    effectTags = {OptionEffectTag.UNKNOWN},
-    help = "Whether to use the experimental local disk cache."
-  )
-  public boolean experimentalLocalDiskCache;
-
-  @Option(
-    name = "experimental_local_disk_cache_path",
+    name = "build_cache",
     defaultValue = "null",
     category = "remote",
     documentationCategory = OptionDocumentationCategory.UNCATEGORIZED,
     effectTags = {OptionEffectTag.UNKNOWN},
     converter = OptionsUtils.PathFragmentConverter.class,
-    help = "A file path to a local disk cache."
+    help = "A path to a directory where Bazel can read and write actions and action outputs. "
+        + "If the directory does not exist, it will be created."
   )
-  public PathFragment experimentalLocalDiskCachePath;
+  public PathFragment buildCache;
 
   @Option(
     name = "experimental_guard_against_concurrent_changes",

src/main/java/com/google/devtools/build/lib/remote/SimpleBlobStoreFactory.java

@@ -46,10 +46,10 @@ public static SimpleBlobStore createRest(RemoteOptions options, Credentials cred
     }
   }
 
-  public static SimpleBlobStore createLocalDisk(RemoteOptions options, Path workingDirectory)
+  public static SimpleBlobStore createBuildCache(RemoteOptions options, Path workingDirectory)
       throws IOException {
     return new OnDiskBlobStore(
-        workingDirectory.getRelative(checkNotNull(options.experimentalLocalDiskCachePath)));
+        workingDirectory.getRelative(checkNotNull(options.buildCache)));
   }
 
   public static SimpleBlobStore create(
@@ -58,20 +58,20 @@ public static SimpleBlobStore create(
     if (isRestUrlOptions(options)) {
       return createRest(options, creds);
     }
-    if (workingDirectory != null && isLocalDiskCache(options)) {
-      return createLocalDisk(options, workingDirectory);
+    if (workingDirectory != null && isBuildCache(options)) {
+      return createBuildCache(options, workingDirectory);
     }
     throw new IllegalArgumentException(
         "Unrecognized concurrent map RemoteOptions: must specify "
             + "either Rest URL, or local cache options.");
   }
 
   public static boolean isRemoteCacheOptions(RemoteOptions options) {
-    return isRestUrlOptions(options) || isLocalDiskCache(options);
+    return isRestUrlOptions(options) || isBuildCache(options);
   }
 
-  public static boolean isLocalDiskCache(RemoteOptions options) {
-    return options.experimentalLocalDiskCache;
+  public static boolean isBuildCache(RemoteOptions options) {
+    return options.buildCache != null;
   }
 
   private static boolean isRestUrlOptions(RemoteOptions options) {

src/test/shell/bazel/BUILD

@@ -318,9 +318,9 @@ sh_test(
 )
 
 sh_test(
-    name = "local_action_cache_test",
+    name = "build_cache_test",
     size = "small",
-    srcs = ["local_action_cache_test.sh"],
+    srcs = ["build_cache_test.sh"],
     data = [":test-deps"],
 )
 

src/test/shell/bazel/local_action_cache_test.sh → src/test/shell/bazel/build_cache_test.sh

@@ -27,7 +27,7 @@ function test_local_action_cache() {
   local execution_file="${TEST_TMPDIR}/run.log"
   local input_file="foo.in"
   local output_file="bazel-genfiles/foo.txt"
-  local flags="--experimental_local_disk_cache_path=$cache --experimental_local_disk_cache"
+  local flags="--build_cache=$cache"
 
   rm -rf $cache
   mkdir $cache