Report on download cache look up and archive extraction

Checking an entry in the download cache or a distdir might take a
while, as the hash of that file has to be computed. Extracting an
archive can take even more time, as that usually implies a lot of
disk IO. Inform the user about the progress here to avoid confusing
this delay with network activity.

Change-Id: I86316529309960a8a501b96ae752a12a554197b9
PiperOrigin-RevId: 284140963

src/main/java/com/google/devtools/build/lib/bazel/repository/downloader/HttpDownloader.java

@@ -129,13 +129,17 @@ public Path download(
       String cacheKey = checksum.get().toString();
       KeyType cacheKeyType = checksum.get().getKeyType();
       try {
+        eventHandler.post(
+            new CacheProgress(mainUrl.toString(), "Checking in " + cacheKeyType + " cache"));
         String currentChecksum = RepositoryCache.getChecksum(cacheKeyType, destination);
         if (currentChecksum.equals(cacheKey)) {
           // No need to download.
           return destination;
         }
       } catch (IOException e) {
         // Ignore error trying to hash. We'll attempt to retrieve from cache or just download again.
+      } finally {
+        eventHandler.post(new CacheProgress(mainUrl.toString()));
       }
 
       if (repositoryCache.isEnabled()) {
@@ -171,11 +175,16 @@ public Path download(
             boolean match = false;
             Path candidate = dir.getRelative(name);
             try {
+              eventHandler.post(
+                  new CacheProgress(
+                      mainUrl.toString(), "Checking " + cacheKeyType + " of " + candidate));
               match = RepositoryCache.getChecksum(cacheKeyType, candidate).equals(cacheKey);
             } catch (IOException e) {
               // Not finding anything in a distdir is a normal case, so handle it absolutely
               // quietly. In fact, it is common to specify a whole list of dist dirs,
               // with the assumption that only one will contain an entry.
+            } finally {
+              eventHandler.post(new CacheProgress(mainUrl.toString()));
             }
             if (match) {
               if (isCachingByProvidedChecksum) {
@@ -304,4 +313,37 @@ private static ImmutableSet<String> getCandidateFileNames(URL url, Path destinat
       return ImmutableSet.of(destination.getBaseName());
     }
   }
+
+  private static class CacheProgress implements ExtendedEventHandler.FetchProgress {
+    private final String originalUrl;
+    private final String progress;
+    private final boolean isFinished;
+
+    CacheProgress(String originalUrl, String progress) {
+      this.originalUrl = originalUrl;
+      this.progress = progress;
+      this.isFinished = false;
+    }
+
+    CacheProgress(String originalUrl) {
+      this.originalUrl = originalUrl;
+      this.progress = "";
+      this.isFinished = true;
+    }
+
+    @Override
+    public String getResourceIdentifier() {
+      return originalUrl;
+    }
+
+    @Override
+    public String getProgress() {
+      return progress;
+    }
+
+    @Override
+    public boolean isFinished() {
+      return isFinished;
+    }
+  }
 }

src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryContext.java

@@ -713,6 +713,10 @@ public void extract(Object archive, Object output, String stripPrefix, Location
             location);
     env.getListener().post(w);
 
+    env.getListener()
+        .post(
+            new ExtractProgress(
+                outputPath.getPath().toString(), "Extracting " + archivePath.getPath()));
     DecompressorValue.decompress(
         DecompressorDescriptor.builder()
             .setTargetKind(rule.getTargetKind())
@@ -721,6 +725,7 @@ public void extract(Object archive, Object output, String stripPrefix, Location
             .setRepositoryPath(outputPath.getPath())
             .setPrefix(stripPrefix)
             .build());
+    env.getListener().post(new ExtractProgress(outputPath.getPath().toString()));
   }
 
   @Override
@@ -803,6 +808,9 @@ public StructImpl downloadAndExtract(
     env.getListener().post(w);
     try (SilentCloseable c =
         Profiler.instance().profile("extracting: " + rule.getLabel().toString())) {
+      env.getListener()
+          .post(
+              new ExtractProgress(outputPath.getPath().toString(), "Extracting " + downloadedPath));
       DecompressorValue.decompress(
           DecompressorDescriptor.builder()
               .setTargetKind(rule.getTargetKind())
@@ -811,6 +819,7 @@ public StructImpl downloadAndExtract(
               .setRepositoryPath(outputPath.getPath())
               .setPrefix(stripPrefix)
               .build());
+      env.getListener().post(new ExtractProgress(outputPath.getPath().toString()));
     }
 
     StructImpl downloadResult = calculateDownloadResult(checksum, downloadedPath);
@@ -1085,4 +1094,37 @@ private static Map<URI, Map<String, String>> getAuthHeaders(Map<String, Dict<?,
     }
     return headers.build();
   }
+
+  private static class ExtractProgress implements FetchProgress {
+    private final String repositoryPath;
+    private final String progress;
+    private final boolean isFinished;
+
+    ExtractProgress(String repositoryPath, String progress) {
+      this.repositoryPath = repositoryPath;
+      this.progress = progress;
+      this.isFinished = false;
+    }
+
+    ExtractProgress(String repositoryPath) {
+      this.repositoryPath = repositoryPath;
+      this.progress = "";
+      this.isFinished = true;
+    }
+
+    @Override
+    public String getResourceIdentifier() {
+      return repositoryPath;
+    }
+
+    @Override
+    public String getProgress() {
+      return progress;
+    }
+
+    @Override
+    public boolean isFinished() {
+      return isFinished;
+    }
+  }
 }