android: allow using normal RUST_LOG filters for rust code

platform/jvm/capture/src/main/kotlin/io/bitdrift/capture/Capture.kt

@@ -527,16 +527,20 @@ object Capture {
     }
 
     /**
-     * Usage: adb shell setprop debug.bitdrift.internal_log_level debug
-     * Sets up the internal logging level for the rust library. This is done by reading a system
+     * Usage: adb shell setprop debug.bitdrift.internal_rust_log debug
+     * Sets up the internal logging filter for the rust library. This is done by reading a system
      * property and propagating it as an environment variable within the same process.
      * It swallows any failures and sets default to "info".
+     *
+     * This supports normal rust log filters, so for example so look at trace logs for only bd
+     * crates to:
+     * adb shell setprop debug.bitdrift.internal_rust_log info,bd=trace
      */
     @Suppress("SpreadOperator")
     @SuppressLint("PrivateApi")
     private fun setUpInternalLogging(context: Context) {
         if (BuildTypeChecker.isDebuggable(context)) {
-            val defaultLevel = "info"
+            val defaultRustLog = "info"
             runCatching {
                 // TODO(murki): Alternatively we could use JVM -D arg to pass properties
                 //  that can be read via System.getProperty() but that's less Android-idiomatic
@@ -545,11 +549,11 @@ object Capture {
                 Class
                     .forName("android.os.SystemProperties")
                     .getMethod("get", *arrayOf(String::class.java, String::class.java))
-                    .invoke(null, *arrayOf("debug.bitdrift.internal_log_level", defaultLevel)) as? String
+                    .invoke(null, *arrayOf("debug.bitdrift.internal_rust_log", defaultRustLog)) as? String
             }.getOrNull().let {
-                val internalLogLevel = it ?: defaultLevel
+                val internalRustLog = it ?: defaultRustLog
                 runCatching {
-                    Os.setenv("RUST_LOG", internalLogLevel, true)
+                    Os.setenv("RUST_LOG", internalRustLog, true)
                 }
             }
         }

platform/jvm/src/jni.rs

@@ -63,7 +63,7 @@ use time::{Duration, OffsetDateTime};
 // Android to avoid setting this up in JVM tests where we want to log to stderr.
 #[cfg(target_os = "android")]
 fn initialize_logging() {
-  use android_logger::Config;
+  use android_logger::{Config, FilterBuilder};
   use log::LevelFilter;
   use std::sync::Once;
 
@@ -73,13 +73,14 @@ fn initialize_logging() {
     // TODO(snowp): Ideally we use a tracing subscriber which embeds the span information like we
     // do everywhere else, as that would let us use trace spans to provide context for the logs.
     // Look into forking `tracing-android`.
-    let level = std::env::var("RUST_LOG")
-      .unwrap_or_else(|_| "info".to_string())
-      .parse::<LevelFilter>()
-      .unwrap_or(LevelFilter::Info);
+    let rust_log = std::env::var("RUST_LOG").unwrap_or_else(|_| "info".to_string());
 
     // This can be called only once.
-    android_logger::init_once(Config::default().with_max_level(level));
+    android_logger::init_once(
+      Config::default()
+        .with_max_level(LevelFilter::Trace)
+        .with_filter(FilterBuilder::new().parse(&rust_log).build()),
+    );
   });
 }