Don't get corrupted when journal writing fails.

Closes square#1211

Working towards square#746

okhttp-tests/src/test/java/com/squareup/okhttp/internal/DiskLruCacheTest.java

@@ -16,7 +16,6 @@
 package com.squareup.okhttp.internal;
 
 import com.squareup.okhttp.internal.io.FileSystem;
-import com.squareup.okhttp.internal.io.InMemoryFileSystem;
 import java.io.File;
 import java.io.IOException;
 import java.util.ArrayDeque;
@@ -53,7 +52,7 @@ public final class DiskLruCacheTest {
   @Rule public final TemporaryFolder tempDir = new TemporaryFolder();
   @Rule public final Timeout timeout = new Timeout(30 * 1000);
 
-  private final FileSystem fileSystem = FileSystem.SYSTEM;
+  private final FaultyFileSystem fileSystem = new FaultyFileSystem(FileSystem.SYSTEM);
   private final int appVersion = 100;
   private File cacheDir;
   private File journalFile;
@@ -1070,6 +1069,95 @@ private void createNewCacheWithSize(int maxSize) throws IOException {
     assertTrue(cache.isClosed());
   }
 
+  @Test public void journalWriteFailsDuringEdit() throws Exception {
+    set("a", "a", "a");
+    set("b", "b", "b");
+
+    // We can't begin the edit if writing 'DIRTY' fails.
+    fileSystem.setFaulty(journalFile, true);
+    assertNull(cache.edit("c"));
+
+    // Once the journal has a failure, subsequent writes aren't permitted.
+    fileSystem.setFaulty(journalFile, false);
+    assertNull(cache.edit("d"));
+
+    // Confirm that the fault didn't corrupt entries stored before the fault was introduced.
+    cache.close();
+    cache = new DiskLruCache(fileSystem, cacheDir, appVersion, 2, Integer.MAX_VALUE, executor);
+    assertValue("a", "a", "a");
+    assertValue("b", "b", "b");
+    assertAbsent("c");
+    assertAbsent("d");
+  }
+
+  /**
+   * We had a bug where the cache was left in an inconsistent state after a journal write failed.
+   * https://github.com/square/okhttp/issues/1211
+   */
+  @Test public void journalWriteFailsDuringEditorCommit() throws Exception {
+    set("a", "a", "a");
+    set("b", "b", "b");
+
+    // Create an entry that fails to write to the journal during commit.
+    DiskLruCache.Editor editor = cache.edit("c");
+    setString(editor, 0, "c");
+    setString(editor, 1, "c");
+    fileSystem.setFaulty(journalFile, true);
+    editor.commit();
+
+    // Once the journal has a failure, subsequent writes aren't permitted.
+    fileSystem.setFaulty(journalFile, false);
+    assertNull(cache.edit("d"));
+
+    // Confirm that the fault didn't corrupt entries stored before the fault was introduced.
+    cache.close();
+    cache = new DiskLruCache(fileSystem, cacheDir, appVersion, 2, Integer.MAX_VALUE, executor);
+    assertValue("a", "a", "a");
+    assertValue("b", "b", "b");
+    assertAbsent("c");
+    assertAbsent("d");
+  }
+
+  @Test public void journalWriteFailsDuringEditorAbort() throws Exception {
+    set("a", "a", "a");
+    set("b", "b", "b");
+
+    // Create an entry that fails to write to the journal during abort.
+    DiskLruCache.Editor editor = cache.edit("c");
+    setString(editor, 0, "c");
+    setString(editor, 1, "c");
+    fileSystem.setFaulty(journalFile, true);
+    editor.abort();
+
+    // Once the journal has a failure, subsequent writes aren't permitted.
+    fileSystem.setFaulty(journalFile, false);
+    assertNull(cache.edit("d"));
+
+    // Confirm that the fault didn't corrupt entries stored before the fault was introduced.
+    cache.close();
+    cache = new DiskLruCache(fileSystem, cacheDir, appVersion, 2, Integer.MAX_VALUE, executor);
+    assertValue("a", "a", "a");
+    assertValue("b", "b", "b");
+    assertAbsent("c");
+    assertAbsent("d");
+  }
+
+  @Test public void journalWriteFailsDuringRemove() throws Exception {
+    set("a", "a", "a");
+    set("b", "b", "b");
+
+    // Remove, but the journal write will fail.
+    fileSystem.setFaulty(journalFile, true);
+    assertTrue(cache.remove("a"));
+
+    // Confirm that the entry was still removed.
+    fileSystem.setFaulty(journalFile, false);
+    cache.close();
+    cache = new DiskLruCache(fileSystem, cacheDir, appVersion, 2, Integer.MAX_VALUE, executor);
+    assertAbsent("a");
+    assertValue("b", "b", "b");
+  }
+
   private void assertJournalEquals(String... expectedBodyLines) throws Exception {
     List<String> expectedLines = new ArrayList<>();
     expectedLines.add(MAGIC);

okhttp-tests/src/test/java/com/squareup/okhttp/internal/FaultyFileSystem.java

@@ -0,0 +1,90 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.squareup.okhttp.internal;
+
+import com.squareup.okhttp.internal.io.FileSystem;
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.util.LinkedHashSet;
+import java.util.Set;
+import okio.Buffer;
+import okio.ForwardingSink;
+import okio.Sink;
+import okio.Source;
+
+public final class FaultyFileSystem implements FileSystem {
+  private final FileSystem delegate;
+  private final Set<File> writeFaults = new LinkedHashSet<>();
+
+  public FaultyFileSystem(FileSystem delegate) {
+    this.delegate = delegate;
+  }
+
+  public void setFaulty(File file, boolean faulty) {
+    if (faulty) {
+      writeFaults.add(file);
+    } else {
+      writeFaults.remove(file);
+    }
+  }
+
+  @Override public Source source(File file) throws FileNotFoundException {
+    return delegate.source(file);
+  }
+
+  @Override public Sink sink(File file) throws FileNotFoundException {
+    return new FaultySink(delegate.sink(file), file);
+  }
+
+  @Override public Sink appendingSink(File file) throws FileNotFoundException {
+    return new FaultySink(delegate.appendingSink(file), file);
+  }
+
+  @Override public void delete(File file) throws IOException {
+    delegate.delete(file);
+  }
+
+  @Override public boolean exists(File file) throws IOException {
+    return delegate.exists(file);
+  }
+
+  @Override public long size(File file) {
+    return delegate.size(file);
+  }
+
+  @Override public void rename(File from, File to) throws IOException {
+    delegate.rename(from, to);
+  }
+
+  @Override public void deleteContents(File directory) throws IOException {
+    delegate.deleteContents(directory);
+  }
+
+  private class FaultySink extends ForwardingSink {
+    private final File file;
+
+    public FaultySink(Sink delegate, File file) {
+      super(delegate);
+      this.file = file;
+    }
+
+    @Override public void write(Buffer source, long byteCount) throws IOException {
+      if (writeFaults.contains(file)) throw new IOException("boom!");
+      super.write(source, byteCount);
+    }
+  }
+}

okhttp/src/main/java/com/squareup/okhttp/internal/DiskLruCache.java

@@ -36,7 +36,6 @@
 import okio.Buffer;
 import okio.BufferedSink;
 import okio.BufferedSource;
-import okio.ForwardingSink;
 import okio.Okio;
 import okio.Sink;
 import okio.Source;
@@ -151,6 +150,7 @@ public final class DiskLruCache implements Closeable {
   private BufferedSink journalWriter;
   private final LinkedHashMap<String, Entry> lruEntries = new LinkedHashMap<>(0, 0.75f, true);
   private int redundantOpCount;
+  private boolean hasJournalErrors;
 
   // Must be read and written when synchronized on 'this'.
   private boolean initialized;
@@ -291,13 +291,24 @@ private void readJournal() throws IOException {
       if (!source.exhausted()) {
         rebuildJournal();
       } else {
-        journalWriter = Okio.buffer(fileSystem.appendingSink(journalFile));
+        journalWriter = newJournalWriter();
       }
     } finally {
       Util.closeQuietly(source);
     }
   }
 
+  private BufferedSink newJournalWriter() throws FileNotFoundException {
+    Sink fileSink = fileSystem.appendingSink(journalFile);
+    Sink faultHidingSink = new FaultHidingSink(fileSink) {
+      @Override protected void onException(IOException e) {
+        assert (Thread.holdsLock(DiskLruCache.this));
+        hasJournalErrors = true;
+      }
+    };
+    return Okio.buffer(faultHidingSink);
+  }
+
   private void readJournalLine(String line) throws IOException {
     int firstSpace = line.indexOf(' ');
     if (firstSpace == -1) {
@@ -399,7 +410,8 @@ private synchronized void rebuildJournal() throws IOException {
     fileSystem.rename(journalFileTmp, journalFile);
     fileSystem.delete(journalFileBackup);
 
-    journalWriter = Okio.buffer(fileSystem.appendingSink(journalFile));
+    journalWriter = newJournalWriter();
+    hasJournalErrors = false;
   }
 
   /**
@@ -445,19 +457,24 @@ private synchronized Editor edit(String key, long expectedSequenceNumber) throws
         || entry.sequenceNumber != expectedSequenceNumber)) {
       return null; // Snapshot is stale.
     }
-    if (entry == null) {
-      entry = new Entry(key);
-      lruEntries.put(key, entry);
-    } else if (entry.currentEditor != null) {
+    if (entry != null && entry.currentEditor != null) {
       return null; // Another edit is in progress.
     }
 
-    Editor editor = new Editor(entry);
-    entry.currentEditor = editor;
-
     // Flush the journal before creating files to prevent file leaks.
     journalWriter.writeUtf8(DIRTY).writeByte(' ').writeUtf8(key).writeByte('\n');
     journalWriter.flush();
+
+    if (hasJournalErrors) {
+      return null; // Don't edit; the journal can't be written.
+    }
+
+    if (entry == null) {
+      entry = new Entry(key);
+      lruEntries.put(key, entry);
+    }
+    Editor editor = new Editor(entry);
+    entry.currentEditor = editor;
     return editor;
   }
 
@@ -860,7 +877,13 @@ public Sink newSink(int index) throws IOException {
         } catch (FileNotFoundException e) {
           return NULL_SINK;
         }
-        return new FaultHidingSink(sink);
+        return new FaultHidingSink(sink) {
+          @Override protected void onException(IOException e) {
+            synchronized (DiskLruCache.this) {
+              hasErrors = true;
+            }
+          }
+        };
       }
     }
 
@@ -900,42 +923,6 @@ public void abortUnlessCommitted() {
         }
       }
     }
-
-    private class FaultHidingSink extends ForwardingSink {
-      public FaultHidingSink(Sink delegate) {
-        super(delegate);
-      }
-
-      @Override public void write(Buffer source, long byteCount) throws IOException {
-        try {
-          super.write(source, byteCount);
-        } catch (IOException e) {
-          synchronized (DiskLruCache.this) {
-            hasErrors = true;
-          }
-        }
-      }
-
-      @Override public void flush() throws IOException {
-        try {
-          super.flush();
-        } catch (IOException e) {
-          synchronized (DiskLruCache.this) {
-            hasErrors = true;
-          }
-        }
-      }
-
-      @Override public void close() throws IOException {
-        try {
-          super.close();
-        } catch (IOException e) {
-          synchronized (DiskLruCache.this) {
-            hasErrors = true;
-          }
-        }
-      }
-    }
   }
 
   private final class Entry {

okhttp/src/main/java/com/squareup/okhttp/internal/FaultHidingSink.java

@@ -0,0 +1,51 @@
+package com.squareup.okhttp.internal;
+
+import java.io.IOException;
+import okio.Buffer;
+import okio.ForwardingSink;
+import okio.Sink;
+
+/** A sink that never throws IOExceptions, even if the underlying sink does. */
+class FaultHidingSink extends ForwardingSink {
+  private boolean hasErrors;
+
+  public FaultHidingSink(Sink delegate) {
+    super(delegate);
+  }
+
+  @Override public void write(Buffer source, long byteCount) throws IOException {
+    if (hasErrors) {
+      source.skip(byteCount);
+      return;
+    }
+    try {
+      super.write(source, byteCount);
+    } catch (IOException e) {
+      hasErrors = true;
+      onException(e);
+    }
+  }
+
+  @Override public void flush() throws IOException {
+    if (hasErrors) return;
+    try {
+      super.flush();
+    } catch (IOException e) {
+      hasErrors = true;
+      onException(e);
+    }
+  }
+
+  @Override public void close() throws IOException {
+    if (hasErrors) return;
+    try {
+      super.close();
+    } catch (IOException e) {
+      hasErrors = true;
+      onException(e);
+    }
+  }
+
+  protected void onException(IOException e) {
+  }
+}