refactor: optimize logging system

This commit addresses a series of fixes, refactors,
and documentation changes meant to optimize the new
logging system to be better with:

- Improved memory usage by eliminating unnecessary data
  allocations and improving log record handling.

- Enhanced logging system with support for foreign
  implementations (as tested with Kotlin).

- Improved documentation across board.

- Cleaner refactors and simpler code that improve
  clarity.

- Streamlined logging configuration.

- Pre-existing bug fixes.

Cargo.toml

@@ -80,7 +80,7 @@ libc = "0.2"
 uniffi = { version = "0.27.3", features = ["build"], optional = true }
 serde = { version = "1.0.210", default-features = false, features = ["std", "derive"] }
 serde_json = { version = "1.0.128", default-features = false, features = ["std"] }
-log = { version = "0.4.22", features = ["std"]}
+log = { version = "0.4.22", default-features = false, features = ["std"]}
 
 vss-client = "0.3"
 prost = { version = "0.11.6", default-features = false}

bindings/kotlin/ldk-node-android/lib/src/androidTest/kotlin/org/lightningdevkit/ldknode/AndroidLibTest.kt

@@ -3,19 +3,16 @@
  */
 package org.lightningdevkit.ldknode
 
-import kotlin.UInt
-import kotlin.test.Test
-import kotlin.test.assertEquals
+import androidx.test.ext.junit.runners.AndroidJUnit4
 import kotlin.io.path.createTempDirectory
+import kotlin.test.Test
 import org.junit.runner.RunWith
-import org.lightningdevkit.ldknode.*;
-import android.content.Context.MODE_PRIVATE
-import androidx.test.core.app.ApplicationProvider
-import androidx.test.ext.junit.runners.AndroidJUnit4
+import org.lightningdevkit.ldknode.*
 
 @RunWith(AndroidJUnit4::class)
 class AndroidLibTest {
-    @Test fun node_start_stop() {
+    @Test
+    fun node_start_stop() {
         val tmpDir1 = createTempDirectory("ldk_node").toString()
         println("Random dir 1: $tmpDir1")
         val tmpDir2 = createTempDirectory("ldk_node").toString()

bindings/kotlin/ldk-node-jvm/lib/src/test/kotlin/org/lightningdevkit/ldknode/LibraryTest.kt

@@ -9,6 +9,7 @@ import java.net.http.HttpRequest
 import java.net.http.HttpResponse
 import kotlin.io.path.createTempDirectory
 import kotlin.test.assertEquals
+import kotlin.test.assertTrue
 
 fun runCommandAndWait(vararg cmd: String): String {
     println("Running command \"${cmd.joinToString(" ")}\"")
@@ -92,6 +93,60 @@ fun waitForBlock(esploraEndpoint: String, blockHash: String) {
     }
 }
 
+class CustomLogWriter(private var currentLogLevel: LogLevel = LogLevel.INFO) :
+    LogWriter {
+    enum class LogLevel {
+        ERROR, WARN, INFO, DEBUG, TRACE, GOSSIP
+    }
+
+    private val logMessages = mutableListOf<String>()
+
+    fun setLogLevel(level: LogLevel) {
+        currentLogLevel = level
+    }
+
+    fun getLogMessages(): List<String> {
+        return logMessages.toList()
+    }
+
+    override fun log(record: LogRecord) {
+        val recordLevel =
+            when (record.level.toString().lowercase()) {
+                "error" -> LogLevel.ERROR
+                "warn" -> LogLevel.WARN
+                "info" -> LogLevel.INFO
+                "debug" -> LogLevel.DEBUG
+                "trace" -> LogLevel.TRACE
+                "gossip" -> LogLevel.GOSSIP
+                else -> LogLevel.INFO
+            }
+
+        if (isLevelEnabled(recordLevel)) {
+            val logMessage = formatRecord(record)
+            logMessages.add(logMessage)
+            println("$logMessage")
+        }
+    }
+
+    private fun formatRecord(record: LogRecord): String {
+        val timestamp =
+            java.time.LocalDateTime.now()
+                .format(java.time.format.DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"))
+        return String.format(
+            "%s %-6s [%s:%s] %s\n",
+            timestamp,
+            record.level,
+            record.modulePath,
+            record.line,
+            record.args
+        )
+    }
+
+    private fun isLevelEnabled(level: LogLevel): Boolean {
+        return level.ordinal <= currentLogLevel.ordinal
+    }
+}
+
 @TestInstance(TestInstance.Lifecycle.PER_CLASS)
 class LibraryTest {
 
@@ -106,6 +161,9 @@ class LibraryTest {
     }
 
     @Test fun fullCycle() {
+        val logWriter1 = CustomLogWriter(CustomLogWriter.LogLevel.GOSSIP)
+        val logWriter2 = CustomLogWriter(CustomLogWriter.LogLevel.GOSSIP)
+
         val tmpDir1 = createTempDirectory("ldk_node").toString()
         println("Random dir 1: $tmpDir1")
         val tmpDir2 = createTempDirectory("ldk_node").toString()
@@ -129,8 +187,11 @@ class LibraryTest {
 
         val builder1 = Builder.fromConfig(config1)
         builder1.setChainSourceEsplora(esploraEndpoint, null)
+        builder1.setCustomLogger(logWriter1)
+
         val builder2 = Builder.fromConfig(config2)
         builder2.setChainSourceEsplora(esploraEndpoint, null)
+        builder2.setCustomLogger(logWriter2)
 
         val node1 = builder1.build()
         val node2 = builder2.build()
@@ -263,6 +324,9 @@ class LibraryTest {
         assert(spendableBalance1AfterClose < 100000u)
         assertEquals(102500uL, spendableBalance2AfterClose)
 
+        assertTrue(logWriter1.getLogMessages().isNotEmpty())
+        assertTrue(logWriter2.getLogMessages().isNotEmpty())
+
         node1.stop()
         node2.stop()
     }

bindings/ldk_node.udl

@@ -34,13 +34,16 @@ enum LogLevel {
 	"Error",
 };
 
-dictionary FilesystemLoggerConfig {
-	string log_file_path;
+dictionary LogRecord {
 	LogLevel level;
+	string args;
+	string module_path;
+	u32 line;
 };
 
-dictionary LogFacadeLoggerConfig {
-	LogLevel level;
+[Trait, WithForeign]
+interface LogWriter {
+    void log(LogRecord record);
 };
 
 interface Builder {
@@ -57,8 +60,9 @@ interface Builder {
 	void set_gossip_source_rgs(string rgs_server_url);
 	void set_liquidity_source_lsps2(SocketAddress address, PublicKey node_id, string? token);
 	void set_storage_dir_path(string storage_dir_path);
-	void set_filesystem_logger(FilesystemLoggerConfig fs_config);
-	void set_log_facade_logger(LogFacadeLoggerConfig lf_config);
+	void set_filesystem_logger(string? log_file_path, LogLevel? log_level);
+	void set_log_facade_logger(LogLevel log_level);
+	void set_custom_logger(LogWriter log_writer);
 	void set_network(Network network);
 	[Throws=BuildError]
 	void set_listening_addresses(sequence<SocketAddress> listening_addresses);
@@ -593,18 +597,6 @@ dictionary NodeAnnouncementInfo {
 	sequence<SocketAddress> addresses;
 };
 
-dictionary LogRecord {
-	LogLevel level;
-	string args;
-	string module_path;
-	u32 line;
-};
-
-[Trait]
-interface LogWriter {
-    void log(LogRecord record);
-};
-
 [Custom]
 typedef string Txid;