Generalize OTEL API and add memcache tracing support

- Rename RedisSpan -> SpanHandle for generic span handling
- Generalize TelemetryController methods: startSpan/endSpan with dbSystem param
- Rename RedisOtelSpan -> OtelSpanHandle in rbcs-server-otel
- Update Redis cache handler to use new generic API
- Add OpenTelemetry tracing for memcache GET and SET commands
- Add channel property to MemcacheRequestController for server address attribution
- Add uses TelemetryController directive in memcache module-info

Memcache spans follow the same pattern as Redis:
db.system=memcache, db.operation=GET|SET, server.address, server.port

gradle.properties

@@ -4,7 +4,7 @@ org.gradle.caching=true
 
 rbcs.version = 0.5.0
 
-lys.version = 2026.05.16
+lys.version = 2026.05.27
 
 gitea.maven.url = https://gitea.woggioni.net/api/packages/woggioni/maven
 docker.registry.url=gitea.woggioni.net

rbcs-api/src/main/java/net/woggioni/rbcs/api/SpanHandle.java

@@ -2,9 +2,12 @@ package net.woggioni.rbcs.api;
 
 import org.jetbrains.annotations.NotNull;
 
-public interface RedisSpan {
+public interface SpanHandle {
 
     void setAttribute(@NotNull String key, @NotNull String value);
 
     void setAttribute(@NotNull String key, long value);
+
+    void setAttribute(@NotNull String key, boolean value);
+
 }

rbcs-api/src/main/java/net/woggioni/rbcs/api/TelemetryController.java

@@ -4,13 +4,15 @@ import io.netty.channel.ChannelHandler;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.Map;
+
 public interface TelemetryController {
     void initialize();
     @NotNull ChannelHandler createHandler();
 
-    @Nullable RedisSpan startRedisSpan(@NotNull String command, @NotNull String key);
+    @Nullable SpanHandle startSpan(@NotNull String command);
 
-    void endRedisSpan(@Nullable RedisSpan span);
+    void endSpan(@Nullable SpanHandle span);
 
-    void endRedisSpan(@Nullable RedisSpan span, @NotNull Throwable error);
+    void endSpan(@Nullable SpanHandle span, @NotNull Throwable error);
 }

rbcs-server-memcache/src/main/java/module-info.java

@@ -1,4 +1,5 @@
 import net.woggioni.rbcs.api.CacheProvider;
+import net.woggioni.rbcs.api.TelemetryController;
 
 module net.woggioni.rbcs.server.memcache {
     requires net.woggioni.rbcs.common;
@@ -16,5 +17,7 @@ module net.woggioni.rbcs.server.memcache {
 
     provides CacheProvider with net.woggioni.rbcs.server.memcache.MemcacheCacheProvider;
 
+    uses TelemetryController;
+
     opens net.woggioni.rbcs.server.memcache.schema;
 }

rbcs-server-memcache/src/main/kotlin/net/woggioni/rbcs/server/memcache/MemcacheCacheHandler.kt

@@ -9,9 +9,11 @@ import java.nio.channels.FileChannel
 import java.nio.channels.ReadableByteChannel
 import java.nio.file.Files
 import java.nio.file.StandardOpenOption
+import java.net.InetSocketAddress
 import java.time.Duration
 import java.time.Instant
 import java.util.concurrent.CompletableFuture
+import java.util.concurrent.atomic.AtomicReference
 import java.util.zip.Deflater
 import java.util.zip.DeflaterOutputStream
 import java.util.zip.InflaterOutputStream
@@ -39,8 +41,11 @@ import net.woggioni.rbcs.api.message.CacheMessage.CachePutResponse
 import net.woggioni.rbcs.api.message.CacheMessage.CacheValueFoundResponse
 import net.woggioni.rbcs.api.message.CacheMessage.CacheValueNotFoundResponse
 import net.woggioni.rbcs.api.message.CacheMessage.LastCacheContent
+import net.woggioni.rbcs.api.SpanHandle
+import net.woggioni.rbcs.api.TelemetryController
 import net.woggioni.rbcs.common.ByteBufInputStream
 import net.woggioni.rbcs.common.ByteBufOutputStream
+import net.woggioni.rbcs.common.RBCS.loadService
 import net.woggioni.rbcs.common.RBCS.processCacheKey
 import net.woggioni.rbcs.common.RBCS.toIntOrNull
 import net.woggioni.rbcs.common.createLogger
@@ -70,6 +75,10 @@ class MemcacheCacheHandler(
         }
     }
 
+    private val telemetryController by lazy {
+        loadService(TelemetryController::class.java).firstOrNull()
+    }
+
     private interface InProgressRequest {
 
     }
@@ -153,7 +162,9 @@ class MemcacheCacheHandler(
         metadata: CacheValueMetadata,
         val digest: ByteBuf,
         val requestController: CompletableFuture<MemcacheRequestController>,
-        private val alloc: ByteBufAllocator
+        private val alloc: ByteBufAllocator,
+        val entryKey: String,
+        val memcacheSpanRef: AtomicReference<SpanHandle?>,
     ) : InProgressRequest {
         private var totalSize = 0
         private var tmpFile: FileChannel? = null
@@ -251,6 +262,17 @@ class MemcacheCacheHandler(
         val key = ctx.alloc().buffer().also {
             it.writeBytes(processCacheKey(msg.key, keyPrefix, digestAlgorithm))
         }
+        val memcacheSpan = telemetryController?.startSpan("GET")?.apply {
+            setAttribute("db.system", "memcache")
+            setAttribute("db.operation.name", "GET")
+            val remoteAddr = ctx.channel().remoteAddress()
+            if (remoteAddr is InetSocketAddress) {
+                remoteAddr.hostString?.let {
+                    setAttribute("server.address", it)
+                }
+                setAttribute("server.port", remoteAddr.port.toLong())
+            }
+        }
         val responseHandler = object : MemcacheResponseHandler {
             override fun responseReceived(response: BinaryMemcacheResponse) {
                 val status = response.status()
@@ -266,8 +288,15 @@ class MemcacheCacheHandler(
                         log.debug(ctx) {
                             "Cache miss for key ${msg.key} on memcache"
                         }
+                        telemetryController?.endSpan(memcacheSpan)
                         sendMessageAndFlush(ctx, CacheValueNotFoundResponse(msg.key))
                     }
+
+                    else -> {
+                        val ex = MemcacheException(status)
+                        telemetryController?.endSpan(memcacheSpan, ex)
+                        this@MemcacheCacheHandler.exceptionCaught(ctx, ex)
+                    }
                 }
             }
 
@@ -282,11 +311,13 @@ class MemcacheCacheHandler(
                     if (content is LastMemcacheContent) {
                         inProgressRequest = null
                         inProgressGetRequest.commit()
+                        telemetryController?.endSpan(memcacheSpan)
                     }
                 }
             }
 
             override fun exceptionCaught(ex: Throwable) {
+                telemetryController?.endSpan(memcacheSpan, ex)
                 (inProgressRequest as? InProgressGetRequest).let { inProgressGetRequest ->
                     inProgressGetRequest?.let {
                         inProgressRequest = null
@@ -312,6 +343,7 @@ class MemcacheCacheHandler(
         val key = ctx.alloc().buffer().also {
             it.writeBytes(processCacheKey(msg.key, keyPrefix, digestAlgorithm))
         }
+        val memcacheSpanRef = AtomicReference<SpanHandle?>(null)
         val responseHandler = object : MemcacheResponseHandler {
             override fun responseReceived(response: BinaryMemcacheResponse) {
                 val status = response.status()
@@ -320,16 +352,22 @@ class MemcacheCacheHandler(
                         log.debug(ctx) {
                             "Inserted key ${msg.key} into memcache"
                         }
+                        telemetryController?.endSpan(memcacheSpanRef.get())
                         sendMessageAndFlush(ctx, CachePutResponse(msg.key))
                     }
 
-                    else -> this@MemcacheCacheHandler.exceptionCaught(ctx, MemcacheException(status))
+                    else -> {
+                        val ex = MemcacheException(status)
+                        telemetryController?.endSpan(memcacheSpanRef.get(), ex)
+                        this@MemcacheCacheHandler.exceptionCaught(ctx, ex)
+                    }
                 }
             }
 
             override fun contentReceived(content: MemcacheContent) {}
 
             override fun exceptionCaught(ex: Throwable) {
+                telemetryController?.endSpan(memcacheSpanRef.get(), ex)
                 this@MemcacheCacheHandler.exceptionCaught(ctx, ex)
             }
         }
@@ -339,7 +377,7 @@ class MemcacheCacheHandler(
                 this@MemcacheCacheHandler.exceptionCaught(ctx, ex)
             }
         }
-        inProgressRequest = InProgressPutRequest(ctx.channel(), msg.metadata, key, requestController, ctx.alloc())
+        inProgressRequest = InProgressPutRequest(ctx.channel(), msg.metadata, key, requestController, ctx.alloc(), msg.key, memcacheSpanRef)
     }
 
     private fun handleCacheContent(ctx: ChannelHandlerContext, msg: CacheContent) {
@@ -362,22 +400,41 @@ class MemcacheCacheHandler(
         val request = inProgressRequest
         when (request) {
             is InProgressPutRequest -> {
+                val putRequest = request
                 inProgressRequest = null
                 log.trace(ctx) {
                     "Received last chunk of ${msg.content().readableBytes()} bytes for memcache"
                 }
-                request.write(msg.content())
+                putRequest.write(msg.content())
-                val key = request.digest.retainedDuplicate()
+                val memcacheSpan = telemetryController?.startSpan("SET",
-                val (payloadSize, payloadSource) = request.commit()
+                )?.apply {
+                    setAttribute("db.system", "memcache")
+                    setAttribute("db.operation.name", "SET")
+                    val remoteAddr = ctx.channel().remoteAddress()
+                    if (remoteAddr is InetSocketAddress) {
+                        remoteAddr.hostString?.let {
+                            setAttribute("server.address", it)
+                        }
+                        setAttribute("server.port", remoteAddr.port.toLong())
+                    }
+                }
+                putRequest.memcacheSpanRef.set(memcacheSpan)
+                val key = putRequest.digest.retainedDuplicate()
+                val (payloadSize, payloadSource) = putRequest.commit()
                 val extras = ctx.alloc().buffer(8, 8)
                 extras.writeInt(0)
                 extras.writeInt(encodeExpiry(maxAge))
-                val totalBodyLength = request.digest.readableBytes() + extras.readableBytes() + payloadSize
+                val totalBodyLength = putRequest.digest.readableBytes() + extras.readableBytes() + payloadSize
                 log.trace(ctx) {
                     "Trying to send SET request to memcache"
                 }
-                request.requestController.whenComplete { requestController, ex ->
+                putRequest.requestController.whenComplete { requestController, ex ->
                     if (ex == null) {
+                        val remoteAddr = requestController.channel.remoteAddress()
+                        if (remoteAddr is InetSocketAddress) {
+                            remoteAddr.hostString?.let { memcacheSpan?.setAttribute("server.address", it) }
+                            memcacheSpan?.setAttribute("server.port", remoteAddr.port.toLong())
+                        }
                         log.trace(ctx) {
                             "Sending SET request to memcache"
                         }

rbcs-server-memcache/src/main/kotlin/net/woggioni/rbcs/server/memcache/client/MemcacheClient.kt

@@ -147,6 +147,8 @@ class MemcacheClient(
 
                     channel.pipeline().addLast(handler)
                     response.complete(object : MemcacheRequestController {
+                        override val channel: Channel = channel
+
                         private var channelReleased = false
 
                         override fun sendRequest(request: BinaryMemcacheRequest) {

rbcs-server-memcache/src/main/kotlin/net/woggioni/rbcs/server/memcache/client/MemcacheRequestController.kt

@@ -1,10 +1,13 @@
 package net.woggioni.rbcs.server.memcache.client
 
+import io.netty.channel.Channel
 import io.netty.handler.codec.memcache.MemcacheContent
 import io.netty.handler.codec.memcache.binary.BinaryMemcacheRequest
 
 interface MemcacheRequestController {
 
+    val channel: Channel
+
     fun sendRequest(request : BinaryMemcacheRequest)
 
     fun sendContent(content : MemcacheContent)

rbcs-server-otel/src/main/kotlin/net/woggioni/rbcs/server/otel/OtelController.kt

@@ -2,13 +2,14 @@ package net.woggioni.rbcs.server.otel
 
 import io.netty.channel.ChannelHandler
 import io.opentelemetry.api.GlobalOpenTelemetry
+import io.opentelemetry.api.common.AttributeKey
 import io.opentelemetry.api.trace.SpanKind
 import io.opentelemetry.api.trace.StatusCode
 import io.opentelemetry.instrumentation.logback.appender.v1_0.OpenTelemetryAppender
 import io.opentelemetry.instrumentation.netty.v4_1.NettyServerTelemetry
 import io.opentelemetry.instrumentation.runtimetelemetry.RuntimeTelemetry
 import io.opentelemetry.sdk.autoconfigure.AutoConfiguredOpenTelemetrySdk
-import net.woggioni.rbcs.api.RedisSpan
+import net.woggioni.rbcs.api.SpanHandle
 import net.woggioni.rbcs.api.TelemetryController
 import net.woggioni.rbcs.common.createLogger
 import net.woggioni.rbcs.common.info
@@ -44,21 +45,19 @@ class OtelController : TelemetryController {
         return NettyServerTelemetry.create(GlobalOpenTelemetry.get()).createCombinedHandler()
     }
 
-    override fun startRedisSpan(command: String, key: String): RedisSpan? {
+    override fun startSpan(name: String): SpanHandle {
-        val span = tracer.spanBuilder(command)
+        val span = tracer.spanBuilder(name)
             .setSpanKind(SpanKind.CLIENT)
-            .setAttribute("db.system", "redis")
-            .setAttribute("db.operation", command)
             .startSpan()
-        return RedisOtelSpan(span)
+        return OtelSpanHandle(span)
     }
 
-    override fun endRedisSpan(span: RedisSpan?) {
+    override fun endSpan(span: SpanHandle?) {
-        (span as? RedisOtelSpan)?.delegate?.end()
+        (span as? OtelSpanHandle)?.delegate?.end()
     }
 
-    override fun endRedisSpan(span: RedisSpan?, error: Throwable) {
+    override fun endSpan(span: SpanHandle?, error: Throwable) {
-        val s = (span as? RedisOtelSpan)?.delegate ?: return
+        val s = (span as? OtelSpanHandle)?.delegate ?: return
         s.recordException(error)
         s.setStatus(StatusCode.ERROR)
         s.end()

rbcs-server-otel/src/main/kotlin/net/woggioni/rbcs/server/otel/OtelSpanHandle.kt

@@ -1,11 +1,11 @@
 package net.woggioni.rbcs.server.otel
 
 import io.opentelemetry.api.trace.Span
-import net.woggioni.rbcs.api.RedisSpan
+import net.woggioni.rbcs.api.SpanHandle
 
-internal class RedisOtelSpan(
+internal class OtelSpanHandle(
     val delegate: Span,
-) : RedisSpan {
+) : SpanHandle {
 
     override fun setAttribute(key: String, value: String) {
         delegate.setAttribute(key, value)
@@ -14,4 +14,8 @@ internal class RedisOtelSpan(
     override fun setAttribute(key: String, value: Long) {
         delegate.setAttribute(key, value)
     }
+
+    override fun setAttribute(key: String, value: Boolean) {
+        delegate.setAttribute(key, value)
+    }
 }

rbcs-server-redis/src/main/kotlin/net/woggioni/rbcs/server/redis/RedisCacheHandler.kt

@@ -36,7 +36,6 @@ import net.woggioni.rbcs.api.message.CacheMessage.CachePutResponse
 import net.woggioni.rbcs.api.message.CacheMessage.CacheValueFoundResponse
 import net.woggioni.rbcs.api.message.CacheMessage.CacheValueNotFoundResponse
 import net.woggioni.rbcs.api.message.CacheMessage.LastCacheContent
-import net.woggioni.rbcs.api.RedisSpan
 import net.woggioni.rbcs.api.TelemetryController
 import net.woggioni.rbcs.common.ByteBufInputStream
 import net.woggioni.rbcs.common.ByteBufOutputStream
@@ -250,21 +249,32 @@ class RedisCacheHandler(
         }
         val keyBytes = processCacheKey(msg.key, keyPrefix, digestAlgorithm)
         val keyString = String(keyBytes, StandardCharsets.UTF_8)
-        val redisSpan = telemetryController?.startRedisSpan("GET", keyString)
+        val redisSpan = telemetryController?.startSpan("GET")?.apply {
+            setAttribute("db.system", "redis")
+            setAttribute("db.operation.name", "GET")
+            val remoteAddr = ctx.channel().remoteAddress()
+            if (remoteAddr is InetSocketAddress) {
+                remoteAddr.hostString?.let {
+                    setAttribute("server.address", it)
+                }
+                setAttribute("server.port", remoteAddr.port.toLong())
+            }
+        }
         val responseHandler = object : RedisResponseHandler {
             override fun responseReceived(response: RedisMessage) {
-                try {
                 when (response) {
                     is FullBulkStringRedisMessage -> {
                         if (response === FullBulkStringRedisMessage.NULL_INSTANCE || response.content().readableBytes() == 0) {
                             log.debug(ctx) {
                                 "Cache miss for key ${msg.key} on Redis"
                             }
+                            telemetryController?.endSpan(redisSpan)
                             sendMessageAndFlush(ctx, CacheValueNotFoundResponse(msg.key))
                         } else {
                             log.debug(ctx) {
                                 "Cache hit for key ${msg.key} on Redis"
                             }
+                            telemetryController?.endSpan(redisSpan)
                             val getRequest = InProgressGetRequest(msg.key, ctx)
                             inProgressRequest = getRequest
                             getRequest.processResponse(response.content())
@@ -274,7 +284,7 @@ class RedisCacheHandler(
 
                     is ErrorRedisMessage -> {
                         val ex = RedisException("Redis error for GET ${msg.key}: ${response.content()}")
-                            telemetryController?.endRedisSpan(redisSpan, ex)
+                        telemetryController?.endSpan(redisSpan, ex)
                         this@RedisCacheHandler.exceptionCaught(ctx, ex)
                     }
 
@@ -282,16 +292,14 @@ class RedisCacheHandler(
                         log.warn(ctx) {
                             "Unexpected response type from Redis for key ${msg.key}: ${response.javaClass.name}"
                         }
+                        telemetryController?.endSpan(redisSpan)
                         sendMessageAndFlush(ctx, CacheValueNotFoundResponse(msg.key))
                     }
                 }
-                } finally {
-                    telemetryController?.endRedisSpan(redisSpan)
-                }
             }
 
             override fun exceptionCaught(ex: Throwable) {
-                telemetryController?.endRedisSpan(redisSpan, ex)
+                telemetryController?.endSpan(redisSpan, ex)
                 this@RedisCacheHandler.exceptionCaught(ctx, ex)
             }
         }
@@ -361,38 +369,45 @@ class RedisCacheHandler(
 
                 val expirySeconds = maxAge.toSeconds().toString()
 
-                val redisSpan = telemetryController?.startRedisSpan("SET", request.keyString)
+                val redisSpan = telemetryController?.startSpan("SET")?.apply {
+                    setAttribute("db.system", "redis")
+                    setAttribute("db.operation.name", "SET")
+                    val remoteAddr = ctx.channel().remoteAddress()
+                    if (remoteAddr is InetSocketAddress) {
+                        remoteAddr.hostString?.let {
+                            setAttribute("server.address", it)
+                        }
+                        setAttribute("server.port", remoteAddr.port.toLong())
+                    }
+                }
 
                 val responseHandler = object : RedisResponseHandler {
                     override fun responseReceived(response: RedisMessage) {
-                        try {
                         when (response) {
                             is SimpleStringRedisMessage -> {
                                 log.debug(ctx) {
                                     "Inserted key ${request.keyString} into Redis"
                                 }
+                                telemetryController?.endSpan(redisSpan)
                                 sendMessageAndFlush(ctx, CachePutResponse(request.keyString))
                             }
 
                             is ErrorRedisMessage -> {
                                 val ex = RedisException("Redis error for SET ${request.keyString}: ${response.content()}")
-                                    telemetryController?.endRedisSpan(redisSpan, ex)
+                                telemetryController?.endSpan(redisSpan, ex)
                                 this@RedisCacheHandler.exceptionCaught(ctx, ex)
                             }
 
                             else -> {
                                 val ex = RedisException("Unexpected response for SET ${request.keyString}: ${response.javaClass.name}")
-                                    telemetryController?.endRedisSpan(redisSpan, ex)
+                                telemetryController?.endSpan(redisSpan, ex)
                                 this@RedisCacheHandler.exceptionCaught(ctx, ex)
                             }
                         }
-                        } finally {
-                            telemetryController?.endRedisSpan(redisSpan)
-                        }
                     }
 
                     override fun exceptionCaught(ex: Throwable) {
-                        telemetryController?.endRedisSpan(redisSpan, ex)
+                        telemetryController?.endSpan(redisSpan, ex)
                         this@RedisCacheHandler.exceptionCaught(ctx, ex)
                     }
                 }