DfsBlockCacheConfigs: add debug configuration print

This will write out configuration values on a line by line basis to a
given PrintWriter.
Primary usage is as a semi-formatted debug print of the configuration
values used by dfs block cache.

Change-Id: I96724262245e4aa3423734a8b10de83322c4f89f

2 files changed, 97 insertions, 1 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsBlockCacheConfigTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsBlockCacheConfigTest.java
index 4b7aae05f0..65774e6d6c 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsBlockCacheConfigTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsBlockCacheConfigTest.java
@@ -54,7 +54,12 @@ import static org.hamcrest.Matchers.hasSize;
 import static org.hamcrest.Matchers.is;
 import static org.junit.Assert.assertThrows;
 
+import java.io.ByteArrayOutputStream;
+import java.io.PrintWriter;
+import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
 import java.util.List;
+import java.util.Map;
 import java.util.stream.Collectors;
 
 import org.eclipse.jgit.internal.JGitText;
@@ -250,6 +255,45 @@ public class DfsBlockCacheConfigTest {
 				() -> new DfsBlockCacheConfig().fromConfig(config));
 	}
 
+	@Test
+	public void writeConfigurationDebug_writesConfigsToWriter()
+			throws Exception {
+		Config config = new Config();
+		config.setLong(CONFIG_CORE_SECTION, CONFIG_DFS_SECTION,
+				CONFIG_KEY_BLOCK_LIMIT, 50 * 1024);
+		config.setInt(CONFIG_CORE_SECTION, CONFIG_DFS_SECTION,
+				CONFIG_KEY_BLOCK_SIZE, 1024);
+		config.setInt(CONFIG_CORE_SECTION, CONFIG_DFS_SECTION,
+				CONFIG_KEY_CONCURRENCY_LEVEL, 3);
+		config.setString(CONFIG_CORE_SECTION, CONFIG_DFS_SECTION,
+				CONFIG_KEY_STREAM_RATIO, "0.5");
+		addPackExtConfigEntry(config, "pack", List.of(PackExt.PACK),
+				/* blockLimit= */ 20 * 512, /* blockSize= */ 512);
+
+		DfsBlockCacheConfig cacheConfig = new DfsBlockCacheConfig()
+				.fromConfig(config);
+		Map<PackExt, Integer> hotmap = Map.of(PackExt.PACK, 10);
+		cacheConfig.setCacheHotMap(hotmap);
+
+		ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
+		cacheConfig.print(new PrintWriter(byteArrayOutputStream, true,
+				StandardCharsets.UTF_8));
+
+		String writenConfig = byteArrayOutputStream
+				.toString(StandardCharsets.UTF_8);
+
+		List<String> writenLines = Arrays.asList(writenConfig.split("\n"));
+		assertThat(writenLines,
+				equalTo(List.of("Name: dfs", "  BlockLimit: " + (50 * 1024),
+						"  BlockSize: 1024", "  StreamRatio: 0.5",
+						"  ConcurrencyLevel: 3",
+						"  CacheHotMapEntry: " + PackExt.PACK + " : " + 10,
+						"  Name: dfs.pack", "    BlockLimit: " + 20 * 512,
+						"    BlockSize: 512", "    StreamRatio: 0.3",
+						"    ConcurrencyLevel: 32",
+						"    PackExts: " + List.of(PackExt.PACK))));
+	}
+
 	private static void addPackExtConfigEntry(Config config, String configName,
 			List<PackExt> packExts, long blockLimit, int blockSize) {
 		String packExtConfigName = CONFIG_DFS_CACHE_PREFIX + configName;
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsBlockCacheConfig.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsBlockCacheConfig.java
index 52eb9e0785..0d56689a67 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsBlockCacheConfig.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsBlockCacheConfig.java
@@ -19,6 +19,7 @@ import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_CONCURRENCY_LEVEL;
 import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_PACK_EXTENSIONS;
 import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_STREAM_RATIO;
 
+import java.io.PrintWriter;
 import java.text.MessageFormat;
 import java.time.Duration;
 import java.util.ArrayList;
@@ -83,6 +84,51 @@ public class DfsBlockCacheConfig {
 	}
 
 	/**
+	 * Print the current cache configuration to the given {@link PrintWriter}.
+	 *
+	 * @param writer
+	 *            {@link PrintWriter} to write the cache's configuration to.
+	 */
+	public void print(PrintWriter writer) {
+		print(/* linePrefix= */ "", /* pad= */ "  ", writer);
+	}
+
+	/**
+	 * Print the current cache configuration to the given {@link PrintWriter}.
+	 *
+	 * @param linePrefix
+	 *            prefix to prepend all writen lines with. Ex a string of 0 or
+	 *            more " " entries.
+	 * @param pad
+	 *            filler used to extend linePrefix. Ex a multiple of " ".
+	 * @param writer
+	 *            {@link PrintWriter} to write the cache's configuration to.
+	 */
+	private void print(String linePrefix, String pad, PrintWriter writer) {
+		String currentPrefixLevel = linePrefix;
+		if (!name.isEmpty() || !packExtCacheConfigurations.isEmpty()) {
+			String name = this.name;
+			if (name.isEmpty()) {
+				name = "<Default>";
+			}
+			writer.println(linePrefix + "Name: " + name);
+			currentPrefixLevel += pad;
+		}
+		writer.println(currentPrefixLevel + "BlockLimit: " + blockLimit);
+		writer.println(currentPrefixLevel + "BlockSize: " + blockSize);
+		writer.println(currentPrefixLevel + "StreamRatio: " + streamRatio);
+		writer.println(
+				currentPrefixLevel + "ConcurrencyLevel: " + concurrencyLevel);
+		for (Map.Entry<PackExt, Integer> entry : cacheHotMap.entrySet()) {
+			writer.println(currentPrefixLevel + "CacheHotMapEntry: "
+					+ entry.getKey() + " : " + entry.getValue());
+		}
+		for (DfsBlockCachePackExtConfig extConfig : packExtCacheConfigurations) {
+			extConfig.print(currentPrefixLevel, pad, writer);
+		}
+	}
+
+	/**
 	 * Get the name for the block cache configured by this cache config.
 	 *
 	 * @return the name for the block cache configured by this cache config.
@@ -531,5 +577,11 @@ public class DfsBlockCacheConfig {
 			return new DfsBlockCachePackExtConfig(EnumSet.copyOf(packExts),
 					dfsBlockCacheConfig);
 		}
+
+		void print(String linePrefix, String pad, PrintWriter writer) {
+			packExtCacheConfiguration.print(linePrefix, pad, writer);
+			writer.println(linePrefix + pad + "PackExts: "
+					+ packExts.stream().sorted().toList());
+		}
 	}
-}
\ No newline at end of file
+}