Add WebhookErrorHandler (#59)

Bump version to 0.8.0

Author: MinnDevelopment

README.md

@@ -3,6 +3,9 @@
 [license]: https://img.shields.io/badge/License-Apache%202.0-lightgrey.svg
 [license-file]: https://github.com/MinnDevelopment/discord-webhooks/blob/master/LICENSE
 
+[WebhookClient#setErrorHandler]: https://minndevelopment.github.io/discord-webhooks/club/minnced/discord/webhook/WebhookClient.html#setErrorHandler(club.minnced.discord.webhook.util.WebhookErrorHandler)
+[WebhookClient#setDefaultErrorHandler]: https://minndevelopment.github.io/discord-webhooks/club/minnced/discord/webhook/WebhookClient.html#setDefaultErrorHandler(club.minnced.discord.webhook.util.WebhookErrorHandler)
+
 [ ![version] ][download]
 [ ![license] ][license-file]
 
@@ -137,6 +140,25 @@ try (WebhookClient client = WebhookClient.withUrl(url)) {
 webhookCluster.close(); // closes each client and can be used again
 ```
 
+## Error Handling
+
+By default, this library will log every exception encountered when sending a message using the SLF4J logger implementation.
+This can be configured using [WebhookClient#setErrorHandler] to custom behavior per client or [WebhookClient#setDefaultErrorHandler] for all clients.
+
+### Example
+
+```java
+WebhookClient.setDefaultErrorHandler((client, message, throwable) -> {
+    System.err.printf("[%s] %s%n", client.getId(), message);
+    if (throwable != null)
+        throwable.printStackTrace();
+    // Shutdown the webhook client when you get 404 response (may also trigger for client#edit calls, be careful)
+    if (throwable instanceof HttpException ex && ex.getCode() == 404) {
+        client.close();
+    }
+});
+```
+
 ## External Libraries
 
 This library also supports sending webhook messages with integration from other libraries such as

build.gradle.kts

@@ -11,8 +11,8 @@ plugins {
 }
 
 val major = "0"
-val minor = "7"
-val patch = "5"
+val minor = "8"
+val patch = "0"
 
 group = "club.minnced"
 version = "$major.$minor.$patch"

src/main/java/club/minnced/discord/webhook/WebhookClient.java

@@ -24,6 +24,7 @@
 import club.minnced.discord.webhook.send.WebhookMessage;
 import club.minnced.discord.webhook.send.WebhookMessageBuilder;
 import club.minnced.discord.webhook.util.ThreadPools;
+import club.minnced.discord.webhook.util.WebhookErrorHandler;
 import okhttp3.OkHttpClient;
 import okhttp3.RequestBody;
 import okhttp3.Response;
@@ -55,6 +56,7 @@ public class WebhookClient implements AutoCloseable {
     /** User-Agent used for REST requests */
     public static final String USER_AGENT = "Webhook(https://github.com/MinnDevelopment/discord-webhooks, " + LibraryInfo.VERSION + ")";
     private static final Logger LOG = LoggerFactory.getLogger(WebhookClient.class);
+    private static WebhookErrorHandler DEFAULT_ERROR_HANDLER = WebhookErrorHandler.DEFAULT;
 
     protected final WebhookClient parent;
 
@@ -70,6 +72,7 @@ public class WebhookClient implements AutoCloseable {
     protected long defaultTimeout;
     protected volatile boolean isQueued;
     protected boolean isShutdown;
+    protected WebhookErrorHandler errorHandler = DEFAULT_ERROR_HANDLER;
 
     protected WebhookClient(
             final long id, final String token, final boolean parseMessage,
@@ -102,6 +105,21 @@ protected WebhookClient(final WebhookClient parent, final long threadId) {
         this.isQueued = false;
     }
 
+    /**
+     * Configures which default error handler to use instead of {@link WebhookErrorHandler#DEFAULT}.
+     *
+     * <p>You can use this to avoid having to set the error handler on each new webhook client instance.
+     *
+     * @param  handler
+     *         The error handler to use
+     *
+     * @throws NullPointerException
+     *         If null is povided
+     */
+    public static void setDefaultErrorHandler(@NotNull WebhookErrorHandler handler) {
+        DEFAULT_ERROR_HANDLER = Objects.requireNonNull(handler, "Error Handler must not be null!");
+    }
+
     /**
      * Factory method to create a basic WebhookClient with the provided id and token.
      *
@@ -238,6 +256,23 @@ public WebhookClient setTimeout(@Nonnegative long millis) {
         return this;
     }
 
+    /**
+     * Configures the error handling behavior used for all asynchronous send/edit/delete calls.
+     *
+     * @param  handler
+     *         The error handler
+     *
+     * @throws java.lang.NullPointerException
+     *         If provided with null
+     *
+     * @return The current WebhookClient instance
+     */
+    @NotNull
+    public WebhookClient setErrorHandler(@NotNull WebhookErrorHandler handler) {
+        this.errorHandler = Objects.requireNonNull(handler, "Error Handler must not be null!");
+        return this;
+    }
+
     /**
      * The current timeout configured by {@link #setTimeout(long)}.
      * <br>If no timeout was configured, this returns 0.
@@ -795,7 +830,7 @@ private boolean executePair(@Async.Execute Request req) {
             }
             else if (!response.isSuccessful()) {
                 final HttpException exception = failure(response);
-                LOG.error("Sending a webhook message failed with non-OK http response", exception);
+                errorHandler.handle(this, "Sending a webhook message failed with non-OK http response", exception);
                 queue.poll().future.completeExceptionally(exception);
                 return true;
             }
@@ -812,7 +847,7 @@ else if (!response.isSuccessful()) {
             }
         }
         catch (JSONException | IOException e) {
-            LOG.error("There was some error while sending a webhook message", e);
+            errorHandler.handle(this, "There was some error while sending a webhook message", e);
             queue.poll().future.completeExceptionally(e);
         }
         return true;
@@ -832,7 +867,7 @@ public String getMethod() {
         }
     }
 
-    protected static final class Bucket {
+    protected final class Bucket {
         public static final int RATE_LIMIT_CODE = 429;
         public long resetTime;
         public int remainingUses;
@@ -899,7 +934,7 @@ public void update(Response response) {
                 update0(response);
             }
             catch (Exception ex) {
-                LOG.error("Could not read http response", ex);
+                errorHandler.handle(WebhookClient.this, "Could not read http response", ex);
             }
         }
     }

src/main/java/club/minnced/discord/webhook/util/WebhookErrorHandler.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2018-2020 Florian Spieß
+ *
+ * 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 club.minnced.discord.webhook.util;
+
+import club.minnced.discord.webhook.WebhookClient;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Used to dynamically handle errors for webhook requests in {@link WebhookClient}
+ * <br>If not explicitly configured, this uses {@link #DEFAULT}.
+ *
+ * @see WebhookClient#setDefaultErrorHandler(WebhookErrorHandler)
+ * @see WebhookClient#setErrorHandler(WebhookErrorHandler)
+ */
+@FunctionalInterface
+public interface WebhookErrorHandler {
+    /**
+     * The default error handling which simply logs the exception using SLF4J
+     */
+    WebhookErrorHandler DEFAULT = (client, message, throwable) -> LoggerFactory.getLogger(WebhookClient.class).error(message, throwable);
+
+    /**
+     * Implements error handling, must not throw anything!
+     *
+     * @param client
+     *        The {@link WebhookClient} instance which encountered the exception
+     * @param message
+     *        The context message used for logging
+     * @param throwable
+     *        The encountered exception, or null if the error is only a context message
+     */
+    void handle(@NotNull WebhookClient client, @NotNull String message, @Nullable Throwable throwable);
+}