Improved tests. Improved defaults of some of configuration parameters and described them in documentation.

README.md

@@ -68,7 +68,7 @@ This example sets up a root logger with a Loki appender.
     </Loggers>
 
     <appenders>
-        <Loki name="Loki">
+        <Loki name="Loki" bufferSizeMegabytes="64">
             <host>${sys:loki.host}</host>
             <port>${sys:loki.port}</port>
 
@@ -112,7 +112,32 @@ a `X-Scope-OrgID` header when [running Loki in multi-tenant mode](https://grafan
 #### Label (optional)
 
 Specify additional labels attached to each log line sent via this appender instance.
-                                                                                                                                                    
+
+#### bufferSizeMegabytes (optional, default = 1MB)
+
+Size of the `log buffer`. Must be power of two between 1MB and 1GB. See https://github.com/tkowalcz/tjahzi/wiki/Log-buffer-sizing for more explanations.
+
+#### maxRetries (optional, default = 3)
+
+Maximum number of retries to perform when delivering log message to Loki. Log buffer data is delivered in order, one batch after
+the other, so too much retries will block delivery of subsequent log batches (on the other hand if we need to retry many times then
+next batches will probably fail too).
+
+#### connectTimeoutMillis (optional, default = 5s)
+
+This configures socket connect timeout when connecting to Loki. After unsuccessful connection attempt it will continue to retry indefinitely
+employing exponential backoff (initial backoff = 250ms, maximum backoff = 30s, multiplier = 3).
+
+#### readTimeoutMillis (optional, default = 60s)
+
+Sets socket read timeout on Loki connection.
+
+#### useOffHeapBuffer (optional, default = true)
+
+Whether Tjahzi should allocate native buffer for `Log buffer` component. We can go into a rabbit hole of divagations what are the
+implications of this. Most important in our view is that having 10s or 100s of MB of space taken out of heap is not very 
+friendly to garbage collector which might have to occasionally copy it around.
+
 # LICENSE
 
 This work is released under MIT license. Feel free to use, copy and modify this work as long as you credit original authors. 

loki-log4j2-appender/src/main/java/pl/tkowalcz/tjahzi/log4j2/LokiAppender.java

@@ -54,13 +54,13 @@ public class LokiAppender extends AbstractAppender {
         private int port;
 
         @PluginBuilderAttribute
-        private int connectTimeoutMillis = 0;
+        private int connectTimeoutMillis = 5000;
 
         @PluginBuilderAttribute
-        private int readTimeoutMillis = 0;
+        private int readTimeoutMillis = 60_000;
 
         @PluginBuilderAttribute
-        private int maxRetries = 0;
+        private int maxRetries = 3;
 
         @PluginBuilderAttribute
         private int bufferSizeMegabytes = 32;

loki-log4j2-appender/src/test/java/pl/tkowalcz/tjahzi/log4j2/BufferSizeConfigurationTest.java

@@ -3,10 +3,6 @@ package pl.tkowalcz.tjahzi.log4j2;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.core.LoggerContext;
 import org.junit.jupiter.api.Test;
-import org.testcontainers.containers.BindMode;
-import org.testcontainers.containers.GenericContainer;
-import org.testcontainers.containers.wait.strategy.Wait;
-import org.testcontainers.junit.jupiter.Container;
 import org.testcontainers.junit.jupiter.Testcontainers;
 
 import java.net.URI;
@@ -17,27 +13,29 @@ import static org.assertj.core.api.Assertions.assertThat;
 @Testcontainers
 class BufferSizeConfigurationTest {
 
-    @Container
-    public GenericContainer loki = new GenericContainer("grafana/loki:latest")
-            .withCommand("-config.file=/etc/loki-config.yaml")
-            .withClasspathResourceMapping("loki-config.yaml",
-                    "/etc/loki-config.yaml",
-                    BindMode.READ_ONLY)
-            .waitingFor(
-                    Wait.forHttp("/ready")
-                            .forPort(3100)
-            )
-            .withExposedPorts(3100);
-
     @Test
-    void shouldSendData() throws URISyntaxException {
+    void shouldUseDefaultWhenLogBufferSizeIsNotSetViaConfiguration() throws URISyntaxException {
         // Given
-        System.setProperty("loki.host", loki.getHost());
-        System.setProperty("loki.port", loki.getFirstMappedPort().toString());
-
         URI uri = getClass()
                 .getClassLoader()
-                .getResource("appender-test-with-custom-settings-log4j2-configuration.xml")
+                .getResource("appender-test-with-buffer-size-megabytes-unset.xml")
+                .toURI();
+
+        // When
+        LoggerContext context = (LoggerContext) LogManager.getContext(false);
+        context.setConfigLocation(uri);
+
+        // Then
+        LokiAppender loki = context.getConfiguration().getAppender("Loki");
+        assertThat(loki.getLoggingSystem().getLogBufferSize()).isEqualTo(32 * 1024 * 1024);
+    }
+
+    @Test
+    void shouldSetLogBufferSizeViaConfiguration() throws URISyntaxException {
+        // Given
+        URI uri = getClass()
+                .getClassLoader()
+                .getResource("appender-test-with-buffer-size-megabytes-set-to-64.xml")
                 .toURI();
 
         // When

loki-log4j2-appender/src/test/resources/appender-test-with-buffer-size-megabytes-unset.xml

@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration status="OFF" shutdownHook="disable" packages="pl.tkowalcz.tjahzi.log4j2">
+    <Loggers>
+        <Root level="INFO">
+            <AppenderRef ref="Loki"/>
+        </Root>
+    </Loggers>
+
+    <appenders>
+        <Loki name="Loki">
+            <host>${sys:loki.host}</host>
+            <port>${sys:loki.port}</port>
+
+            <ThresholdFilter level="ALL"/>
+            <PatternLayout>
+                <Pattern>%X{tid} [%t] %d{MM-dd HH:mm:ss.SSS} %5p %c{1} - %m%n%exception{full}</Pattern>
+            </PatternLayout>
+
+            <Header name="server" value="127.0.0.1"/>
+            <Label name="server" value="127.0.0.1"/>
+        </Loki>
+    </appenders>
+</configuration>

tjahzi-core/src/main/java/pl/tkowalcz/tjahzi/http/ClientConfigurationBuilder.java

@@ -4,7 +4,7 @@ public class ClientConfigurationBuilder {
 
     public static final String DEFAULT_LOG_ENDPOINT = "/loki/api/v1/push";
 
-    public static final int DEFAULT_CONNECT_TIMEOUT_MILLIS = 60_000;
+    public static final int DEFAULT_CONNECT_TIMEOUT_MILLIS = 5_000;
     public static final int DEFAULT_REQUEST_TIMEOUT_MILLIS = 60_000;
 
     public static final int DEFAULT_MAX_RETRIES = 0;