Disk buffering api changes

disk-buffering/src/main/java/io/opentelemetry/contrib/disk/buffering/SignalType.java

@@ -0,0 +1,12 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.contrib.disk.buffering;
+
+public enum SignalType {
+  SPAN,
+  LOG,
+  METRIC
+}

disk-buffering/src/main/java/io/opentelemetry/contrib/disk/buffering/exporters/ExporterCallback.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.contrib.disk.buffering.exporters;
+
+import io.opentelemetry.contrib.disk.buffering.SignalType;
+import javax.annotation.Nullable;
+
+/** Notifies about exporter and storage-related operations from within a signal to disk exporter. */
+public interface ExporterCallback {
+  /**
+   * Called when an export to disk operation succeeded.
+   *
+   * @param type The type of signal associated to the exporter.
+   */
+  void onExportSuccess(SignalType type);
+
+  /**
+   * Called when an export to disk operation failed.
+   *
+   * @param type The type of signal associated to the exporter.
+   * @param error Optional - provides more information of why the operation failed.
+   */
+  void onExportError(SignalType type, @Nullable Throwable error);
+
+  /**
+   * Called when the exporter is closed.
+   *
+   * @param type The type of signal associated to the exporter.
+   */
+  void onShutdown(SignalType type);
+
+  static ExporterCallback noop() {
+    return NoopExporterCallback.INSTANCE;
+  }
+}

disk-buffering/src/main/java/io/opentelemetry/contrib/disk/buffering/exporters/NoopExporterCallback.java

@@ -0,0 +1,24 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.contrib.disk.buffering.exporters;
+
+import io.opentelemetry.contrib.disk.buffering.SignalType;
+import javax.annotation.Nullable;
+
+final class NoopExporterCallback implements ExporterCallback {
+  static final NoopExporterCallback INSTANCE = new NoopExporterCallback();
+
+  private NoopExporterCallback() {}
+
+  @Override
+  public void onExportSuccess(SignalType type) {}
+
+  @Override
+  public void onExportError(SignalType type, @Nullable Throwable error) {}
+
+  @Override
+  public void onShutdown(SignalType type) {}
+}

disk-buffering/src/main/java/io/opentelemetry/contrib/disk/buffering/exporters/SignalStorageExporter.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.contrib.disk.buffering.exporters;
+
+import io.opentelemetry.contrib.disk.buffering.SignalType;
+import io.opentelemetry.contrib.disk.buffering.storage.SignalStorage;
+import io.opentelemetry.contrib.disk.buffering.storage.result.WriteResult;
+import io.opentelemetry.sdk.common.CompletableResultCode;
+import java.time.Duration;
+import java.util.Collection;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+/** Internal utility for common export to disk operations across all exporters. */
+final class SignalStorageExporter<T> {
+  private final SignalStorage<T> storage;
+  private final ExporterCallback callback;
+  private final Duration writeTimeout;
+  private final SignalType type;
+
+  public SignalStorageExporter(
+      SignalStorage<T> storage, ExporterCallback callback, Duration writeTimeout, SignalType type) {
+    this.storage = storage;
+    this.callback = callback;
+    this.writeTimeout = writeTimeout;
+    this.type = type;
+  }
+
+  public CompletableResultCode exportToStorage(Collection<T> items) {
+    CompletableFuture<WriteResult> future = storage.write(items);
+    try {
+      WriteResult operation = future.get(writeTimeout.toMillis(), TimeUnit.MILLISECONDS);
+      if (operation.isSuccessful()) {
+        callback.onExportSuccess(type);
+        return CompletableResultCode.ofSuccess();
+      }
+
+      Throwable error = operation.getError();
+      callback.onExportError(type, error);
+      if (error != null) {
+        return CompletableResultCode.ofExceptionalFailure(error);
+      }
+      return CompletableResultCode.ofFailure();
+    } catch (ExecutionException | InterruptedException | TimeoutException e) {
+      callback.onExportError(type, e);
+      return CompletableResultCode.ofExceptionalFailure(e);
+    }
+  }
+}

disk-buffering/src/main/java/io/opentelemetry/contrib/disk/buffering/exporters/SpanToDiskExporter.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.contrib.disk.buffering.exporters;
+
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import io.opentelemetry.contrib.disk.buffering.SignalType;
+import io.opentelemetry.contrib.disk.buffering.storage.SignalStorage;
+import io.opentelemetry.sdk.common.CompletableResultCode;
+import io.opentelemetry.sdk.trace.data.SpanData;
+import io.opentelemetry.sdk.trace.export.SpanExporter;
+import java.time.Duration;
+import java.util.Collection;
+
+/** Exporter that stores spans into disk. */
+public final class SpanToDiskExporter implements SpanExporter {
+  private final SignalStorageExporter<SpanData> storageExporter;
+  private final ExporterCallback callback;
+  private static final SignalType TYPE = SignalType.SPAN;
+
+  private SpanToDiskExporter(
+      SignalStorageExporter<SpanData> storageExporter, ExporterCallback callback) {
+    this.storageExporter = storageExporter;
+    this.callback = callback;
+  }
+
+  public Builder builder(SignalStorage.Span storage) {
+    return new Builder(storage);
+  }
+
+  @Override
+  public CompletableResultCode export(Collection<SpanData> spans) {
+    return storageExporter.exportToStorage(spans);
+  }
+
+  @Override
+  public CompletableResultCode flush() {
+    return CompletableResultCode.ofSuccess();
+  }
+
+  @Override
+  public CompletableResultCode shutdown() {
+    callback.onShutdown(TYPE);
+    return CompletableResultCode.ofSuccess();
+  }
+
+  public static final class Builder {
+    private final SignalStorage.Span storage;
+    private ExporterCallback callback = ExporterCallback.noop();
+    private Duration writeTimeout = Duration.ofSeconds(10);
+
+    @CanIgnoreReturnValue
+    public Builder setExporterCallback(ExporterCallback value) {
+      callback = value;
+      return this;
+    }
+
+    @CanIgnoreReturnValue
+    public Builder setWriteTimeout(Duration value) {
+      writeTimeout = value;
+      return this;
+    }
+
+    public SpanToDiskExporter build() {
+      SignalStorageExporter<SpanData> storageExporter =
+          new SignalStorageExporter<>(storage, callback, writeTimeout, TYPE);
+      return new SpanToDiskExporter(storageExporter, callback);
+    }
+
+    private Builder(SignalStorage.Span storage) {
+      this.storage = storage;
+    }
+  }
+}

disk-buffering/src/main/java/io/opentelemetry/contrib/disk/buffering/exporters/package-info.java

@@ -0,0 +1,9 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+@ParametersAreNonnullByDefault
+package io.opentelemetry.contrib.disk.buffering.exporters;
+
+import javax.annotation.ParametersAreNonnullByDefault;

disk-buffering/src/main/java/io/opentelemetry/contrib/disk/buffering/internal/storage/FileSpanStorage.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.contrib.disk.buffering.internal.storage;
+
+import io.opentelemetry.contrib.disk.buffering.storage.SignalStorage;
+import io.opentelemetry.contrib.disk.buffering.storage.result.WriteResult;
+import io.opentelemetry.sdk.trace.data.SpanData;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.concurrent.CompletableFuture;
+import javax.annotation.Nonnull;
+
+/** Default storage implementation where items are stored in multiple protobuf files. */
+public final class FileSpanStorage implements SignalStorage.Span {
+
+  @Override
+  public CompletableFuture<WriteResult> write(Collection<SpanData> items) {
+    throw new UnsupportedOperationException("For next PR");
+  }
+
+  @Override
+  public CompletableFuture<WriteResult> clear() {
+    throw new UnsupportedOperationException("For next PR");
+  }
+
+  @Override
+  public void close() {
+    throw new UnsupportedOperationException("For next PR");
+  }
+
+  @Nonnull
+  @Override
+  public Iterator<Collection<SpanData>> iterator() {
+    throw new UnsupportedOperationException("For next PR");
+  }
+}

disk-buffering/src/main/java/io/opentelemetry/contrib/disk/buffering/storage/SignalStorage.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.contrib.disk.buffering.storage;
+
+import io.opentelemetry.contrib.disk.buffering.storage.result.WriteResult;
+import io.opentelemetry.sdk.logs.data.LogRecordData;
+import io.opentelemetry.sdk.metrics.data.MetricData;
+import io.opentelemetry.sdk.trace.data.SpanData;
+import java.io.Closeable;
+import java.util.Collection;
+import java.util.concurrent.CompletableFuture;
+
+/**
+ * Allows writing and iterating over written signal items.
+ *
+ * @param <T> The type of signal data supported.
+ */
+public interface SignalStorage<T> extends Iterable<Collection<T>>, Closeable {
+
+  /**
+   * Stores signal items.
+   *
+   * @param items The items to be stored.
+   * @return A future with {@link WriteResult}.
+   */
+  CompletableFuture<WriteResult> write(Collection<T> items);
+
+  /**
+   * Removes all the previously stored items.
+   *
+   * @return A future with {@link WriteResult}.
+   */
+  CompletableFuture<WriteResult> clear();
+
+  /**
+   * Abstraction for Spans. Implementations should use this instead of {@link SignalStorage}
+   * directly.
+   */
+  interface Span extends SignalStorage<SpanData> {}
+
+  /**
+   * Abstraction for Logs. Implementations should use this instead of {@link SignalStorage}
+   * directly.
+   */
+  interface LogRecord extends SignalStorage<LogRecordData> {}
+
+  /**
+   * Abstraction for Metrics. Implementations should use this instead of {@link SignalStorage}
+   * directly.
+   */
+  interface Metric extends SignalStorage<MetricData> {}
+}

disk-buffering/src/main/java/io/opentelemetry/contrib/disk/buffering/storage/result/DefaultWriteResult.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.contrib.disk.buffering.storage.result;
+
+import javax.annotation.Nullable;
+
+final class DefaultWriteResult implements WriteResult {
+  private final boolean successful;
+  @Nullable private final Throwable error;
+
+  DefaultWriteResult(boolean successful, @Nullable Throwable error) {
+    this.successful = successful;
+    this.error = error;
+  }
+
+  @Override
+  public boolean isSuccessful() {
+    return successful;
+  }
+
+  @Nullable
+  @Override
+  public Throwable getError() {
+    return error;
+  }
+}

disk-buffering/src/main/java/io/opentelemetry/contrib/disk/buffering/storage/result/WriteResult.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.contrib.disk.buffering.storage.result;
+
+import io.opentelemetry.contrib.disk.buffering.storage.SignalStorage;
+import javax.annotation.Nullable;
+
+/** The result of a {@link SignalStorage} write operation. */
+public interface WriteResult {
+  /**
+   * Whether the operation succeeded or not.
+   *
+   * @return `true` if the items have been successfully stored, `false` otherwise.
+   */
+  boolean isSuccessful();
+
+  /**
+   * Provides details of why the operation failed.
+   *
+   * @return The error (if any) for the failed operation. It must be null for successful operations.
+   */
+  @Nullable
+  Throwable getError();
+
+  static WriteResult create(boolean successful, @Nullable Throwable error) {
+    return new DefaultWriteResult(successful, error);
+  }
+}