Add repository override option

RELNOTES: Adds a --override_repository option that takes a repository
name and path. This forces Bazel to use the directory at that path
for the repository. Example usage:
`--override_repository=foo=/home/user/gitroot/foo`.

Fixes #1266

PiperOrigin-RevId: 153599291

3 files changed, 60 insertions, 21 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/repository/LocalRepositoryFunction.java b/src/main/java/com/google/devtools/build/lib/rules/repository/LocalRepositoryFunction.java
index ee387f735d..916569c4cb 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/repository/LocalRepositoryFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/repository/LocalRepositoryFunction.java
@@ -40,14 +40,20 @@ public class LocalRepositoryFunction extends RepositoryFunction {
       BlazeDirectories directories, Environment env, Map<String, String> markerData)
       throws InterruptedException, RepositoryFunctionException {
     PathFragment pathFragment = RepositoryFunction.getTargetPath(rule, directories.getWorkspace());
+    return LocalRepositoryFunction.symlink(outputDirectory, pathFragment, env);
+  }
+
+  public static RepositoryDirectoryValue.Builder symlink(
+      Path source, PathFragment destination, Environment env)
+      throws RepositoryFunctionException, InterruptedException {
     try {
-      outputDirectory.createSymbolicLink(pathFragment);
+      source.createSymbolicLink(destination);
     } catch (IOException e) {
       throw new RepositoryFunctionException(
-          new IOException("Could not create symlink to repository " + pathFragment + ": "
+          new IOException("Could not create symlink to repository " + destination + ": "
               + e.getMessage(), e), Transience.TRANSIENT);
     }
-    FileValue repositoryValue = getRepositoryDirectory(outputDirectory, env);
+    FileValue repositoryValue = getRepositoryDirectory(source, env);
     if (repositoryValue == null) {
       // TODO(bazel-team): If this returns null, we unnecessarily recreate the symlink above on the
       // second execution.
@@ -56,10 +62,10 @@ public class LocalRepositoryFunction extends RepositoryFunction {
 
     if (!repositoryValue.isDirectory()) {
       throw new RepositoryFunctionException(
-          new IOException(rule + " must specify an existing directory"), Transience.TRANSIENT);
+          new IOException(source + " must be an existing directory"), Transience.TRANSIENT);
     }
 
-    return RepositoryDirectoryValue.builder().setPath(outputDirectory);
+    return RepositoryDirectoryValue.builder().setPath(source);
   }
 
   @Override
diff --git a/src/main/java/com/google/devtools/build/lib/rules/repository/RepositoryDelegatorFunction.java b/src/main/java/com/google/devtools/build/lib/rules/repository/RepositoryDelegatorFunction.java
index 771231b72b..259950beda 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/repository/RepositoryDelegatorFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/repository/RepositoryDelegatorFunction.java
@@ -25,10 +25,13 @@ import com.google.devtools.build.lib.packages.RuleFormatter;
 import com.google.devtools.build.lib.rules.repository.RepositoryFunction.RepositoryFunctionException;
 import com.google.devtools.build.lib.skyframe.FileValue;
 import com.google.devtools.build.lib.skyframe.PrecomputedValue;
+import com.google.devtools.build.lib.skyframe.PrecomputedValue.Precomputed;
+import com.google.devtools.build.lib.skyframe.SkyFunctions;
 import com.google.devtools.build.lib.syntax.EvalException;
 import com.google.devtools.build.lib.util.Fingerprint;
 import com.google.devtools.build.lib.vfs.FileSystemUtils;
 import com.google.devtools.build.lib.vfs.Path;
+import com.google.devtools.build.lib.vfs.PathFragment;
 import com.google.devtools.build.skyframe.SkyFunction;
 import com.google.devtools.build.skyframe.SkyFunctionException;
 import com.google.devtools.build.skyframe.SkyFunctionException.Transience;
@@ -49,6 +52,8 @@ import javax.annotation.Nullable;
  * this function.
  */
 public final class RepositoryDelegatorFunction implements SkyFunction {
+  public static final Precomputed<Map<RepositoryName, PathFragment>> REPOSITORY_OVERRIDES =
+      new Precomputed<>(SkyKey.create(SkyFunctions.PRECOMPUTED, "repository_overrides"));
 
   // The marker file version is inject in the rule key digest so the rule key is always different
   // when we decide to update the format.
@@ -93,13 +98,22 @@ public final class RepositoryDelegatorFunction implements SkyFunction {
   public SkyValue compute(SkyKey skyKey, Environment env)
       throws SkyFunctionException, InterruptedException {
     RepositoryName repositoryName = (RepositoryName) skyKey.argument();
-    Rule rule = RepositoryFunction.getRule(repositoryName, null, env);
-    if (rule == null) {
+    BlazeDirectories directories = PrecomputedValue.BLAZE_DIRECTORIES.get(env);
+    Map<RepositoryName, PathFragment> overrides = REPOSITORY_OVERRIDES.get(env);
+    if (env.valuesMissing()) {
       return null;
     }
 
-    BlazeDirectories directories = PrecomputedValue.BLAZE_DIRECTORIES.get(env);
-    if (directories == null) {
+    Path repoRoot = RepositoryFunction.getExternalRepositoryDirectory(directories)
+        .getRelative(repositoryName.strippedName());
+    Path markerPath = getMarkerPath(directories, repositoryName.strippedName());
+    if (overrides.containsKey(repositoryName)) {
+      return setupOverride(
+          repositoryName, overrides.get(repositoryName), env, repoRoot, markerPath);
+    }
+
+    Rule rule = RepositoryFunction.getRule(repositoryName, null, env);
+    if (rule == null) {
       return null;
     }
     RepositoryFunction handler;
@@ -110,23 +124,20 @@ public final class RepositoryDelegatorFunction implements SkyFunction {
     }
     if (handler == null) {
       throw new RepositoryFunctionException(
-          new EvalException(Location.fromFile(directories.getWorkspace().getRelative("WORKSPACE")),
+          new EvalException(
+              Location.fromFile(directories.getWorkspace().getRelative("WORKSPACE")),
               "Could not find handler for " + rule),
           Transience.PERSISTENT);
     }
 
     handler.setClientEnvironment(clientEnvironment);
 
-    Path repoRoot =
-        RepositoryFunction.getExternalRepositoryDirectory(directories).getRelative(rule.getName());
     byte[] ruleSpecificData = handler.getRuleSpecificMarkerData(rule, env);
     if (ruleSpecificData == null) {
       return null;
     }
     String ruleKey = computeRuleKey(rule, ruleSpecificData);
     Map<String, String> markerData = new TreeMap<>();
-    Path markerPath = getMarkerPath(directories, rule);
-
     if (handler.isLocal(rule)) {
       // Local repositories are always fetched because the operation is generally fast and they do
       // not depend on non-local data, so it does not make much sense to try to cache from across
@@ -207,7 +218,7 @@ public final class RepositoryDelegatorFunction implements SkyFunction {
         .setFetchingDelayed().build();
   }
 
-  private final String computeRuleKey(Rule rule, byte[] ruleSpecificData) {
+  private String computeRuleKey(Rule rule, byte[] ruleSpecificData) {
     return new Fingerprint().addBytes(RuleFormatter.serializeRule(rule).build().toByteArray())
         .addBytes(ruleSpecificData)
         .addInt(MARKER_FILE_VERSION).hexDigestAndReset();
@@ -226,7 +237,7 @@ public final class RepositoryDelegatorFunction implements SkyFunction {
    * system is up to date.
    */
   @Nullable
-  private final byte[] isFilesystemUpToDate(Path markerPath, Rule rule, String ruleKey,
+  private byte[] isFilesystemUpToDate(Path markerPath, Rule rule, String ruleKey,
       RepositoryFunction handler, Environment env)
       throws RepositoryFunctionException, InterruptedException {
     try {
@@ -310,7 +321,7 @@ public final class RepositoryDelegatorFunction implements SkyFunction {
     return result.toString();
   }
 
-  private final byte[] writeMarkerFile(
+  private byte[] writeMarkerFile(
       Path markerPath, Map<String, String> markerData, String ruleKey)
       throws RepositoryFunctionException {
     try {
@@ -329,13 +340,30 @@ public final class RepositoryDelegatorFunction implements SkyFunction {
     }
   }
 
-  private static Path getMarkerPath(BlazeDirectories directories, Rule rule) {
+  private static Path getMarkerPath(BlazeDirectories directories, String ruleName) {
     return RepositoryFunction.getExternalRepositoryDirectory(directories)
-        .getChild("@" + rule.getName() + ".marker");
+        .getChild("@" + ruleName + ".marker");
   }
 
   @Override
   public String extractTag(SkyKey skyKey) {
     return null;
   }
+
+  private RepositoryDirectoryValue setupOverride(
+      RepositoryName repositoryName, PathFragment sourcePath, Environment env, Path repoRoot,
+      Path markerPath)
+      throws RepositoryFunctionException, InterruptedException {
+    setupRepositoryRoot(repoRoot);
+    RepositoryDirectoryValue.Builder directoryValue = LocalRepositoryFunction.symlink(
+        repoRoot, sourcePath, env);
+    if (directoryValue == null) {
+      return null;
+    }
+    String ruleKey = new Fingerprint().addBytes(repositoryName.strippedName().getBytes())
+        .addBytes(repoRoot.getFileSystem().getPath(sourcePath).getPathString().getBytes())
+        .addInt(MARKER_FILE_VERSION).hexDigestAndReset();
+    byte[] digest = writeMarkerFile(markerPath, new TreeMap<String, String>(), ruleKey);
+    return directoryValue.setDigest(digest).build();
+  }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/repository/RepositoryFunction.java b/src/main/java/com/google/devtools/build/lib/rules/repository/RepositoryFunction.java
index 51486eda50..8afb6eeb83 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/repository/RepositoryFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/repository/RepositoryFunction.java
@@ -470,7 +470,12 @@ public abstract class RepositoryFunction {
         // function so we get invalidation when the repository is fetched.
         // For the repository directory itself, we cannot depends on the RepositoryDirectoryValue
         // (cycle).
-        env.getValue(RepositoryDirectoryValue.key(RepositoryName.create("@" + repositoryName)));
+        env.getValue(
+            RepositoryDirectoryValue.key(
+                RepositoryName.createFromValidStrippedName(repositoryName)));
+      } else {
+        // Invalidate external/<repo> if the repository overrides change.
+        RepositoryDelegatorFunction.REPOSITORY_OVERRIDES.get(env);
       }
     } catch (RepositoryFunction.RepositoryNotFoundException ex) {
       // The repository we are looking for does not exist so we should depend on the whole
@@ -478,7 +483,7 @@ public abstract class RepositoryFunction {
       // already requested all repository functions from the WORKSPACE file from Skyframe as part
       // of the resolution. Therefore we are safe to ignore that Exception.
       return;
-    } catch (RepositoryFunctionException | LabelSyntaxException ex) {
+    } catch (RepositoryFunctionException ex) {
       // This should never happen.
       throw new IllegalStateException(
           "Repository " + repositoryName + " cannot be resolved for path " + rootedPath, ex);