Support new-style digest functions

Support new-style digest functions.

This PR adds support for new-style digest functions to the remote execution
library code. The remote-apis spec says:

```
// * `digest_function` is a lowercase string form of a `DigestFunction.Value`
//   enum, indicating which digest function was used to compute `hash`. If the
//   digest function used is one of MD5, MURMUR3, SHA1, SHA256, SHA384, SHA512,
//   or VSO, this component MUST be omitted. In that case the server SHOULD
//   infer the digest function using the length of the `hash` and the digest
//   functions announced in the server's capabilities.
```

This is a partial commit for #18658.

Closes #18731.

PiperOrigin-RevId: 543691155
Change-Id: If8c386d923db1b24dff6054c8ab3f783409b7f13

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

@@ -21,6 +21,7 @@
 import static java.util.concurrent.TimeUnit.SECONDS;
 
 import build.bazel.remote.execution.v2.Digest;
+import build.bazel.remote.execution.v2.DigestFunction;
 import com.google.bytestream.ByteStreamGrpc;
 import com.google.bytestream.ByteStreamGrpc.ByteStreamFutureStub;
 import com.google.bytestream.ByteStreamGrpc.ByteStreamStub;
@@ -69,6 +70,7 @@ final class ByteStreamUploader {
   private final CallCredentialsProvider callCredentialsProvider;
   private final long callTimeoutSecs;
   private final RemoteRetrier retrier;
+  private final DigestFunction.Value digestFunction;
 
   @Nullable private final Semaphore openedFilePermits;
 
@@ -89,14 +91,16 @@ final class ByteStreamUploader {
       CallCredentialsProvider callCredentialsProvider,
       long callTimeoutSecs,
       RemoteRetrier retrier,
-      int maximumOpenFiles) {
+      int maximumOpenFiles,
+      DigestFunction.Value digestFunction) {
     checkArgument(callTimeoutSecs > 0, "callTimeoutSecs must be gt 0.");
     this.instanceName = instanceName;
     this.channel = channel;
     this.callCredentialsProvider = callCredentialsProvider;
     this.callTimeoutSecs = callTimeoutSecs;
     this.retrier = retrier;
     this.openedFilePermits = maximumOpenFiles != -1 ? new Semaphore(maximumOpenFiles) : null;
+    this.digestFunction = digestFunction;
   }
 
   @VisibleForTesting
@@ -175,11 +179,34 @@ public ListenableFuture<Void> uploadBlobAsync(
         MoreExecutors.directExecutor());
   }
 
-  private static String buildUploadResourceName(
+  private boolean isOldStyleDigestFunction() {
+    // Old-style digest functions (SHA256, etc) are distinguishable by the length
+    // of their hash alone and do not require extra specification, but newer
+    // digest functions (which may have the same length hashes as the older
+    // functions!) must be explicitly specified in the upload resource name.
+    return digestFunction.getNumber() <= 7;
+  }
+
+  private String buildUploadResourceName(
       String instanceName, UUID uuid, Digest digest, boolean compressed) {
-    String template =
-        compressed ? "uploads/%s/compressed-blobs/zstd/%s/%d" : "uploads/%s/blobs/%s/%d";
-    String resourceName = format(template, uuid, digest.getHash(), digest.getSizeBytes());
+
+    String resourceName;
+
+    if (isOldStyleDigestFunction()) {
+      String template =
+          compressed ? "uploads/%s/compressed-blobs/zstd/%s/%d" : "uploads/%s/blobs/%s/%d";
+      resourceName = format(template, uuid, digest.getHash(), digest.getSizeBytes());
+    } else {
+      String template =
+          compressed ? "uploads/%s/compressed-blobs/zstd/%s/%s/%d" : "uploads/%s/blobs/%s/%s/%d";
+      resourceName =
+          format(
+              template,
+              uuid,
+              Ascii.toLowerCase(digestFunction.getValueDescriptor().getName()),
+              digest.getHash(),
+              digest.getSizeBytes());
+    }
     if (!Strings.isNullOrEmpty(instanceName)) {
       resourceName = instanceName + "/" + resourceName;
     }

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

@@ -22,6 +22,7 @@
 import build.bazel.remote.execution.v2.ContentAddressableStorageGrpc;
 import build.bazel.remote.execution.v2.ContentAddressableStorageGrpc.ContentAddressableStorageFutureStub;
 import build.bazel.remote.execution.v2.Digest;
+import build.bazel.remote.execution.v2.DigestFunction;
 import build.bazel.remote.execution.v2.FindMissingBlobsRequest;
 import build.bazel.remote.execution.v2.FindMissingBlobsResponse;
 import build.bazel.remote.execution.v2.GetActionResultRequest;
@@ -107,7 +108,8 @@ public GrpcCacheClient(
             callCredentialsProvider,
             options.remoteTimeout.getSeconds(),
             retrier,
-            options.maximumOpenFiles);
+            options.maximumOpenFiles,
+            digestUtil.getDigestFunction());
     maxMissingBlobsDigestsPerMessage = computeMaxMissingBlobsDigestsPerMessage();
     Preconditions.checkState(
         maxMissingBlobsDigestsPerMessage > 0, "Error: gRPC message size too small.");
@@ -352,12 +354,24 @@ private ListenableFuture<Void> downloadBlob(
         MoreExecutors.directExecutor());
   }
 
-  public static String getResourceName(String instanceName, Digest digest, boolean compressed) {
+  private static boolean isOldStyleDigestFunction(DigestFunction.Value digestFunction) {
+    // Old-style digest functions (SHA256, etc) are distinguishable by the length
+    // of their hash alone and do not require extra specification, but newer
+    // digest functions (which may have the same length hashes as the older
+    // functions!) must be explicitly specified in the upload resource name.
+    return digestFunction.getNumber() <= 7;
+  }
+
+  public static String getResourceName(
+      String instanceName, Digest digest, boolean compressed, DigestFunction.Value digestFunction) {
     String resourceName = "";
     if (!instanceName.isEmpty()) {
       resourceName += instanceName + "/";
     }
     resourceName += compressed ? "compressed-blobs/zstd/" : "blobs/";
+    if (!isOldStyleDigestFunction(digestFunction)) {
+      resourceName += Ascii.toLowerCase(digestFunction.getValueDescriptor().getName()) + "/";
+    }
     return resourceName + DigestUtil.toString(digest);
   }
 
@@ -369,7 +383,11 @@ private ListenableFuture<Long> requestRead(
       @Nullable Supplier<Digest> digestSupplier,
       Channel channel) {
     String resourceName =
-        getResourceName(options.remoteInstanceName, digest, options.cacheCompression);
+        getResourceName(
+            options.remoteInstanceName,
+            digest,
+            options.cacheCompression,
+            digestUtil.getDigestFunction());
     SettableFuture<Long> future = SettableFuture.create();
     OutputStream out;
     try {