Add log cache log streaming support

cloudfoundry-client-reactor/src/main/java/org/cloudfoundry/reactor/logcache/v1/ReactorLogCacheEndpoints.java

@@ -16,15 +16,23 @@
 
 package org.cloudfoundry.reactor.logcache.v1;
 
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
 import java.util.Map;
+import java.util.concurrent.atomic.AtomicLong;
+import org.cloudfoundry.logcache.v1.Envelope;
+import org.cloudfoundry.logcache.v1.EnvelopeType;
 import org.cloudfoundry.logcache.v1.InfoRequest;
 import org.cloudfoundry.logcache.v1.InfoResponse;
 import org.cloudfoundry.logcache.v1.MetaRequest;
 import org.cloudfoundry.logcache.v1.MetaResponse;
 import org.cloudfoundry.logcache.v1.ReadRequest;
 import org.cloudfoundry.logcache.v1.ReadResponse;
+import org.cloudfoundry.logcache.v1.TailLogsRequest;
 import org.cloudfoundry.reactor.ConnectionContext;
 import org.cloudfoundry.reactor.TokenProvider;
+import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
 final class ReactorLogCacheEndpoints extends AbstractLogCacheOperations {
@@ -48,4 +56,111 @@ Mono<MetaResponse> meta(MetaRequest request) {
     Mono<ReadResponse> read(ReadRequest request) {
         return get(request, ReadResponse.class, "read", request.getSourceId()).checkpoint();
     }
+
+    Mono<ReadResponse> recentLogs(ReadRequest request) {
+        return read(request);
+    }
+
+    /**
+     * Continuously polls Log Cache and emits new {@link Envelope}s as they arrive.
+     *
+     * <p>Mirrors the Go {@code logcache.Walk()} / {@code cf tail --follow} semantics:
+     * <ol>
+     *   <li>Start the cursor at {@code startTime} (defaults to now&nbsp;&minus;&nbsp;5&nbsp;s in
+     *       nanoseconds).</li>
+     *   <li>Issue {@code GET /api/v1/read/{sourceId}?start_time=cursor}.</li>
+     *   <li>Emit every returned envelope in ascending timestamp order and advance
+     *       the cursor to {@code lastTimestamp + 1}.</li>
+     *   <li>When the batch is empty, wait {@code pollInterval} before the next poll.</li>
+     *   <li>Repeat forever – the caller cancels the subscription to stop.</li>
+     * </ol>
+     * Fully non-blocking: no {@code Thread.sleep}.
+     */
+    Flux<Envelope> logsTail(TailLogsRequest request) {
+        long defaultStartNanos = (System.currentTimeMillis() - 5_000L) * 1_000_000L;
+        AtomicLong cursor =
+                new AtomicLong(
+                        request.getStartTime() != null
+                                ? request.getStartTime()
+                                : defaultStartNanos);
+
+        List<EnvelopeType> envelopeTypes =
+                request.getEnvelopeTypes() != null
+                        ? request.getEnvelopeTypes()
+                        : Collections.emptyList();
+        String nameFilter = request.getNameFilter();
+
+        /*
+         * Strategy (mirrors Go's logcache.Walk):
+         *  – Mono.defer builds a fresh ReadRequest from the mutable cursor on every repetition.
+         *  – The Mono returns either the sorted batch (non-empty) or an empty list.
+         *  – flatMapMany turns each batch into a stream of individual Envelope items.
+         *  – repeat() subscribes again after each completion.
+         *  – When the batch was empty we insert a delay via Mono.delay before the next
+         *    repetition so we do not hammer the server. We signal "empty" by returning
+         *    a sentinel Mono<Boolean> (false = was empty, true = had data) and use
+         *    repeatWhen to conditionally delay.
+         */
+        return Flux.defer(
+                        () -> {
+                            // Build the read request from the current cursor position.
+                            ReadRequest.Builder builder =
+                                    ReadRequest.builder()
+                                            .sourceId(request.getSourceId())
+                                            .startTime(cursor.get());
+                            if (!envelopeTypes.isEmpty()) {
+                                builder.envelopeTypes(envelopeTypes);
+                            }
+                            if (nameFilter != null && !nameFilter.isEmpty()) {
+                                builder.nameFilter(nameFilter);
+                            }
+
+                            return read(builder.build())
+                                    .onErrorReturn(ReadResponse.builder().build())
+                                    .flatMapMany(
+                                            resp -> {
+                                                List<Envelope> raw =
+                                                        resp.getEnvelopes() != null
+                                                                ? resp.getEnvelopes().getBatch()
+                                                                : Collections.emptyList();
+
+                                                if (raw.isEmpty()) {
+                                                    // Signal "no data" so repeatWhen can insert the
+                                                    // back-off delay.
+                                                    return Flux.empty();
+                                                }
+
+                                                // Sort ascending by timestamp and advance the
+                                                // cursor.
+                                                List<Envelope> sorted = new ArrayList<>(raw);
+                                                sorted.sort(
+                                                        (a, b) ->
+                                                                Long.compare(
+                                                                        a.getTimestamp() != null
+                                                                                ? a.getTimestamp()
+                                                                                : 0L,
+                                                                        b.getTimestamp() != null
+                                                                                ? b.getTimestamp()
+                                                                                : 0L));
+
+                                                Envelope last = sorted.get(sorted.size() - 1);
+                                                cursor.set(
+                                                        (last.getTimestamp() != null
+                                                                        ? last.getTimestamp()
+                                                                        : cursor.get())
+                                                                + 1);
+
+                                                return Flux.fromIterable(sorted);
+                                            });
+                        })
+                // repeatWhen receives a Flux<Long> where each element is the count of items
+                // emitted in the previous cycle (0 = empty batch → insert delay).
+                .repeatWhen(
+                        companion ->
+                                companion.flatMap(
+                                        count ->
+                                                count == 0
+                                                        ? Mono.delay(request.getPollInterval())
+                                                        : Mono.just(count)));
+    }
 }

cloudfoundry-client-reactor/src/main/java/org/cloudfoundry/reactor/logcache/v1/_ReactorLogCacheClient.java

@@ -16,16 +16,19 @@
 
 package org.cloudfoundry.reactor.logcache.v1;
 
+import org.cloudfoundry.logcache.v1.Envelope;
 import org.cloudfoundry.logcache.v1.InfoRequest;
 import org.cloudfoundry.logcache.v1.InfoResponse;
 import org.cloudfoundry.logcache.v1.LogCacheClient;
 import org.cloudfoundry.logcache.v1.MetaRequest;
 import org.cloudfoundry.logcache.v1.MetaResponse;
 import org.cloudfoundry.logcache.v1.ReadRequest;
 import org.cloudfoundry.logcache.v1.ReadResponse;
+import org.cloudfoundry.logcache.v1.TailLogsRequest;
 import org.cloudfoundry.reactor.ConnectionContext;
 import org.cloudfoundry.reactor.TokenProvider;
 import org.immutables.value.Value;
+import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
 import java.net.URI;
@@ -53,6 +56,16 @@ public Mono<ReadResponse> read(ReadRequest request) {
         return getReactorLogCacheEndpoints().read(request);
     }
 
+    @Override
+    public Mono<ReadResponse> recentLogs(ReadRequest request) {
+        return getReactorLogCacheEndpoints().recentLogs(request);
+    }
+
+    @Override
+    public Flux<Envelope> logsTail(TailLogsRequest request) {
+        return getReactorLogCacheEndpoints().logsTail(request);
+    }
+
     /**
      * The connection context
      */

cloudfoundry-client/src/main/java/org/cloudfoundry/logcache/v1/LogCacheClient.java

@@ -16,6 +16,7 @@
 
 package org.cloudfoundry.logcache.v1;
 
+import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
 /**
@@ -46,4 +47,25 @@ public interface LogCacheClient {
      * @return the read response
      */
     Mono<ReadResponse> read(ReadRequest request);
+
+    /**
+     * Makes the Log Cache RecentLogs /api/v1/read request
+     *
+     * @param request the Recent Logs request
+     * @return the events from the recent logs
+     */
+    Mono<ReadResponse> recentLogs(ReadRequest request);
+
+    /**
+     * Continuously polls the Log Cache /api/v1/read endpoint and streams new {@link Envelope}s
+     * as they appear. This is the Java equivalent of the Go {@code logcache.Walk()} API and
+     * {@code cf tail --follow}.
+     * <p>
+     * The returned {@link Flux} will never complete on its own – unsubscribe (or cancel) it to
+     * stop streaming.
+     *
+     * @param request the tail request (source id, optional filters, poll interval)
+     * @return an infinite stream of envelopes
+     */
+    Flux<Envelope> logsTail(TailLogsRequest request);
 }

cloudfoundry-client/src/main/java/org/cloudfoundry/logcache/v1/_TailLogsRequest.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2013-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.cloudfoundry.logcache.v1;
+
+import org.cloudfoundry.Nullable;
+import org.immutables.value.Value;
+
+import java.time.Duration;
+import java.util.List;
+
+/**
+ * The request options for the Log Cache tail (streaming follow) operation.
+ * This continuously polls the Log Cache /api/v1/read endpoint, emitting new envelopes
+ * as they appear – equivalent to {@code cf tail --follow} or the Go {@code logcache.Walk()} API.
+ */
+@Value.Immutable
+abstract class _TailLogsRequest {
+
+    /**
+     * The source id (application guid or service guid) to stream logs for.
+     */
+    abstract String getSourceId();
+
+    /**
+     * Optional start time (UNIX nanoseconds).  Defaults to "now – 5 seconds" when not set.
+     */
+    @Nullable
+    abstract Long getStartTime();
+
+    /**
+     * Optional envelope type filter.
+     */
+    @Nullable
+    abstract List<EnvelopeType> getEnvelopeTypes();
+
+    /**
+     * Optional regex name filter (requires Log Cache ≥ 2.1.0).
+     */
+    @Nullable
+    abstract String getNameFilter();
+
+    /**
+     * How long to wait between successive polls when no new envelopes are available.
+     * Defaults to 250 ms (matching the Go client's {@code AlwaysRetryBackoff}).
+     */
+    @Value.Default
+    Duration getPollInterval() {
+        return Duration.ofMillis(250);
+    }
+}
+

cloudfoundry-operations/src/main/java/org/cloudfoundry/operations/applications/Applications.java

@@ -17,6 +17,10 @@
 package org.cloudfoundry.operations.applications;
 
 import org.cloudfoundry.doppler.LogMessage;
+import org.cloudfoundry.logcache.v1.Envelope;
+import org.cloudfoundry.logcache.v1.Log;
+import org.cloudfoundry.logcache.v1.ReadRequest;
+import org.cloudfoundry.logcache.v1.TailLogsRequest;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
@@ -126,11 +130,29 @@ public interface Applications {
     @Deprecated
     Flux<LogMessage> logs(LogsRequest request);
 
+    /**
+     * List the applications logs from logCacheClient.
+     * If no messages are available, an empty Flux is returned.
+     *
+     * @param request the application logs request
+     * @return the applications logs
+     */
+    Flux<Log> logsRecent(ReadRequest request);
+
+    /**
+     * Continuously streams application log envelopes from Log Cache by repeatedly polling
+     * the {@code /api/v1/read} endpoint. The returned {@link Flux} is infinite – cancel it
+     * to stop streaming. This is the Java equivalent of {@code cf tail --follow}.
+     *
+     * @param request the tail request (source id, optional filters, poll interval)
+     * @return an infinite stream of envelopes
+     */
+    Flux<Envelope> logsTail(TailLogsRequest request);
+
     /**
      * List the applications logs.
-     * Uses Log Cache under the hood when {@link ApplicationLogsRequest#getRecent()} is {@code true}.
-     * Log streaming still uses Doppler, which is not available in CF deployments following
-     * <a href="https://docs.cloudfoundry.org/loggregator/architecture.html#shared-nothing-architecture">shared-nothing architecture</a>.
+     * Only works with {@code Loggregator < 107.0}, shipped in {@code CFD < 24.3}
+     * and {@code TAS < 4.0}.
      *
      * @param request the application logs request
      * @return the applications logs