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Make interrupt handling in AbstractActionInputPrefetcher actually work.
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The implementation at HEAD was riddled by various bugs:

* Interrupt handling in TransferResult was completely borked
* Exceptions thrown by prefetchFile() did not go through the TransferResult translation mechanism

I have my doubts about whether IOException handling in prefetchFile() works given that it is also affected by the second issue, but at least interrupts work now.

It's amazing what one can accomplish if they bother to write a test case.

RELNOTES: None.
PiperOrigin-RevId: 523963654
Change-Id: Ief3017d7799c8dff0462bc28a131ba87e2625440
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@lberki @copybara-github
lberki authored and copybara-github committed Apr 13, 2023
1 parent 928b102 commit a7b96f4
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Showing 4 changed files with 69 additions and 40 deletions.
73 changes: 39 additions & 34 deletions src/main/java/com/google/devtools/build/lib/remote/AbstractActionInputPrefetcher.java
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Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,6 @@
import static com.google.devtools.build.lib.remote.util.RxFutures.toCompletable;
import static com.google.devtools.build.lib.remote.util.RxFutures.toListenableFuture;
import static com.google.devtools.build.lib.remote.util.RxUtils.mergeBulkTransfer;
import static com.google.devtools.build.lib.remote.util.RxUtils.toTransferResult;

import com.google.auto.value.AutoValue;
import com.google.common.annotations.VisibleForTesting;
Expand All @@ -45,6 +44,7 @@
import com.google.devtools.build.lib.events.Reporter;
import com.google.devtools.build.lib.remote.common.CacheNotFoundException;
import com.google.devtools.build.lib.remote.util.AsyncTaskCache;
import com.google.devtools.build.lib.remote.util.RxUtils;
import com.google.devtools.build.lib.remote.util.RxUtils.TransferResult;
import com.google.devtools.build.lib.remote.util.TempPathGenerator;
import com.google.devtools.build.lib.vfs.FileSystemUtils;
Expand All @@ -53,6 +53,7 @@
import com.google.devtools.build.lib.vfs.PathFragment;
import io.reactivex.rxjava3.core.Completable;
import io.reactivex.rxjava3.core.Flowable;
import io.reactivex.rxjava3.core.Single;
import java.io.IOException;
import java.util.ArrayDeque;
import java.util.ArrayList;
Expand Down Expand Up @@ -311,8 +312,7 @@ public ListenableFuture<Void> prefetchFiles(

Flowable<TransferResult> transfers =
Flowable.fromIterable(files)
.flatMapSingle(
input -> toTransferResult(prefetchFile(dirCtx, metadataSupplier, input, priority)));
.flatMapSingle(input -> prefetchFile(dirCtx, metadataSupplier, input, priority));

Completable prefetch =
Completable.using(
Expand All @@ -321,48 +321,53 @@ public ListenableFuture<Void> prefetchFiles(
return toListenableFuture(prefetch);
}

private Completable prefetchFile(
private Single<TransferResult> prefetchFile(
DirectoryContext dirCtx,
MetadataSupplier metadataSupplier,
ActionInput input,
Priority priority)
throws IOException, InterruptedException {
if (input instanceof VirtualActionInput) {
prefetchVirtualActionInput((VirtualActionInput) input);
return Completable.complete();
}
Priority priority) {
try {
if (input instanceof VirtualActionInput) {
prefetchVirtualActionInput((VirtualActionInput) input);
return Single.just(TransferResult.ok());
}

PathFragment execPath = input.getExecPath();
PathFragment execPath = input.getExecPath();

FileArtifactValue metadata = metadataSupplier.getMetadata(input);
if (metadata == null || !canDownloadFile(execRoot.getRelative(execPath), metadata)) {
return Completable.complete();
}
FileArtifactValue metadata = metadataSupplier.getMetadata(input);
if (metadata == null || !canDownloadFile(execRoot.getRelative(execPath), metadata)) {
return Single.just(TransferResult.ok());
}

@Nullable Symlink symlink = maybeGetSymlink(input, metadata, metadataSupplier);
@Nullable Symlink symlink = maybeGetSymlink(input, metadata, metadataSupplier);

if (symlink != null) {
checkState(execPath.startsWith(symlink.getLinkExecPath()));
execPath =
symlink.getTargetExecPath().getRelative(execPath.relativeTo(symlink.getLinkExecPath()));
}
if (symlink != null) {
checkState(execPath.startsWith(symlink.getLinkExecPath()));
execPath =
symlink.getTargetExecPath().getRelative(execPath.relativeTo(symlink.getLinkExecPath()));
}

@Nullable PathFragment treeRootExecPath = maybeGetTreeRoot(input, metadataSupplier);
@Nullable PathFragment treeRootExecPath = maybeGetTreeRoot(input, metadataSupplier);

Completable result =
downloadFileNoCheckRx(
dirCtx,
execRoot.getRelative(execPath),
treeRootExecPath != null ? execRoot.getRelative(treeRootExecPath) : null,
input,
metadata,
priority);
Completable result =
downloadFileNoCheckRx(
dirCtx,
execRoot.getRelative(execPath),
treeRootExecPath != null ? execRoot.getRelative(treeRootExecPath) : null,
input,
metadata,
priority);

if (symlink != null) {
result = result.andThen(plantSymlink(symlink));
}
if (symlink != null) {
result = result.andThen(plantSymlink(symlink));
}

return result;
return RxUtils.toTransferResult(result);
} catch (IOException e) {
return Single.just(TransferResult.error(e));
} catch (InterruptedException e) {
return Single.just(TransferResult.interrupted());
}
}

/**
Expand Down
12 changes: 6 additions & 6 deletions src/main/java/com/google/devtools/build/lib/remote/util/RxUtils.java
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Original file line number Diff line number Diff line change
Expand Up @@ -55,7 +55,7 @@ public static TransferResult error(IOException error) {

/** Returns {@code true} if the operation succeed. */
public boolean isOk() {
return error == null;
return error == null && !interrupted;
}

/** Returns {@code true} if the operation failed. */
Expand Down Expand Up @@ -116,15 +116,15 @@ void onResult(TransferResult result) {
}

Completable toCompletable() {
if (bulkTransferException == null) {
return Completable.complete();
}

if (interrupted) {
return Completable.error(new InterruptedException());
}

return Completable.error(bulkTransferException);
if (bulkTransferException != null) {
return Completable.error(bulkTransferException);
}

return Completable.complete();
}
}

Expand Down
3 changes: 3 additions & 0 deletions src/main/java/com/google/devtools/build/lib/remote/util/Utils.java
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Original file line number Diff line number Diff line change
Expand Up @@ -74,6 +74,7 @@
import java.util.Locale;
import java.util.Map;
import java.util.concurrent.Callable;
import java.util.concurrent.CancellationException;
import java.util.concurrent.ExecutionException;
import java.util.function.BiFunction;
import javax.annotation.Nullable;
Expand Down Expand Up @@ -104,6 +105,8 @@ public static <T> T getFromFuture(ListenableFuture<T> f, boolean cancelOnInterru
throws IOException, InterruptedException {
try {
return f.get();
} catch (CancellationException e) {
throw new InterruptedException();
} catch (ExecutionException e) {
Throwable cause = e.getCause();
if (cause instanceof InterruptedException) {
Expand Down
21 changes: 21 additions & 0 deletions src/test/java/com/google/devtools/build/lib/remote/ActionInputPrefetcherTestBase.java
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,7 @@
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.SettableFuture;
import com.google.devtools.build.lib.actions.ActionInput;
import com.google.devtools.build.lib.actions.ActionInputPrefetcher.MetadataSupplier;
import com.google.devtools.build.lib.actions.ActionInputPrefetcher.Priority;
import com.google.devtools.build.lib.actions.Artifact;
import com.google.devtools.build.lib.actions.Artifact.SpecialArtifact;
Expand All @@ -59,6 +60,7 @@
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.CancellationException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Semaphore;
import java.util.concurrent.atomic.AtomicBoolean;
Expand Down Expand Up @@ -555,6 +557,25 @@ public void prefetchFiles_multipleThreads_downloadIsNotCancelledByOtherThreads()
assertThat(FileSystemUtils.readContent(artifact.getPath(), UTF_8)).isEqualTo("hello world");
}

@Test
public void prefetchFile_interruptingMetadataSupplier_interruptsDownload() throws Exception {
Map<ActionInput, FileArtifactValue> metadata = new HashMap<>();
Map<HashCode, byte[]> cas = new HashMap<>();
Artifact a1 = createRemoteArtifact("file1", "hello world", metadata, cas);
AbstractActionInputPrefetcher prefetcher = createPrefetcher(cas);

MetadataSupplier interruptedMetadataSupplier =
unused -> {
throw new InterruptedException();
};

ListenableFuture<Void> future =
prefetcher.prefetchFiles(
ImmutableList.of(a1), interruptedMetadataSupplier, Priority.MEDIUM);

assertThrows(CancellationException.class, future::get);
}

@Test
public void prefetchFiles_onInterrupt_deletePartialDownloadedFile() throws Exception {
Semaphore startSemaphore = new Semaphore(0);
Expand Down

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