[DE-1016] Async connection pool (#602)

* ConnectionLoadBalanceTest

* added pipelining option

* async connection pool

* increase test waiting time

* non-blocking AsyncQueue::offer()

* refactoring AsyncQueue

Author: rashtao

core/pom.xml

@@ -8,7 +8,7 @@
         <relativePath>../release-parent</relativePath>
         <groupId>com.arangodb</groupId>
         <artifactId>release-parent</artifactId>
-        <version>7.18.0</version>
+        <version>7.19.0-SNAPSHOT</version>
     </parent>
 
     <name>core</name>

core/src/main/java/com/arangodb/ArangoDB.java

@@ -517,6 +517,17 @@ public Builder chunkSize(final Integer chunkSize) {
             return this;
         }
 
+        /**
+         * Set whether to use requests pipelining in HTTP/1.1 ({@link Protocol#HTTP_JSON} or {@link Protocol#HTTP_VPACK}).
+         *
+         * @param pipelining {@code true} if enabled
+         * @return {@link ArangoDB.Builder}
+         */
+        public Builder pipelining(final Boolean pipelining) {
+            config.setPipelining(pipelining);
+            return this;
+        }
+
         /**
          * Sets the maximum number of connections the built in connection pool will open per host.
          *

core/src/main/java/com/arangodb/config/ArangoConfigProperties.java

@@ -21,6 +21,7 @@ public interface ArangoConfigProperties {
     String KEY_USE_SSL = "useSsl";
     String KEY_VERIFY_HOST = "verifyHost";
     String KEY_CHUNK_SIZE = "chunkSize";
+    String KEY_PIPELINING = "pipelining";
     String KEY_MAX_CONNECTIONS = "maxConnections";
     String KEY_CONNECTION_TTL = "connectionTtl";
     String KEY_KEEP_ALIVE_INTERVAL = "keepAliveInterval";
@@ -110,6 +111,10 @@ default Optional<Integer> getChunkSize() {
         return Optional.empty();
     }
 
+    default Optional<Boolean> getPipelining() {
+        return Optional.empty();
+    }
+
     default Optional<Integer> getMaxConnections() {
         return Optional.empty();
     }

core/src/main/java/com/arangodb/internal/ArangoDefaults.java

@@ -50,6 +50,7 @@ public final class ArangoDefaults {
     public static final Boolean DEFAULT_USE_SSL = false;
     public static final Boolean DEFAULT_VERIFY_HOST = true;
     public static final Integer DEFAULT_CHUNK_SIZE = 30_000;
+    public static final Boolean DEFAULT_PIPELINING = false;
     public static final Boolean DEFAULT_ACQUIRE_HOST_LIST = false;
     public static final Integer DEFAULT_ACQUIRE_HOST_LIST_INTERVAL = 60 * 60 * 1000; // hour
     public static final LoadBalancingStrategy DEFAULT_LOAD_BALANCING_STRATEGY = LoadBalancingStrategy.NONE;

core/src/main/java/com/arangodb/internal/config/ArangoConfig.java

@@ -33,6 +33,7 @@ public class ArangoConfig {
     private SSLContext sslContext;
     private Boolean verifyHost;
     private Integer chunkSize;
+    private Boolean pipelining;
     private Integer maxConnections;
     private Long connectionTtl;
     private Integer keepAliveInterval;
@@ -70,6 +71,7 @@ public void loadProperties(final ArangoConfigProperties properties) {
         useSsl = properties.getUseSsl().orElse(ArangoDefaults.DEFAULT_USE_SSL);
         verifyHost = properties.getVerifyHost().orElse(ArangoDefaults.DEFAULT_VERIFY_HOST);
         chunkSize = properties.getChunkSize().orElse(ArangoDefaults.DEFAULT_CHUNK_SIZE);
+        pipelining = properties.getPipelining().orElse(ArangoDefaults.DEFAULT_PIPELINING);
         // FIXME: make maxConnections field Optional
         maxConnections = properties.getMaxConnections().orElse(null);
         // FIXME: make connectionTtl field Optional
@@ -173,6 +175,14 @@ public void setChunkSize(Integer chunkSize) {
         this.chunkSize = chunkSize;
     }
 
+    public Boolean getPipelining() {
+        return pipelining;
+    }
+
+    public void setPipelining(Boolean pipelining) {
+        this.pipelining = pipelining;
+    }
+
     public Integer getMaxConnections() {
         if (maxConnections == null) {
             maxConnections = getDefaultMaxConnections();

core/src/main/java/com/arangodb/internal/config/ArangoConfigPropertiesImpl.java

@@ -119,6 +119,11 @@ public Optional<Integer> getChunkSize() {
         return Optional.ofNullable(getProperty(KEY_CHUNK_SIZE)).map(Integer::valueOf);
     }
 
+    @Override
+    public Optional<Boolean> getPipelining() {
+        return Optional.ofNullable(getProperty(KEY_PIPELINING)).map(Boolean::valueOf);
+    }
+
     @Override
     public Optional<Integer> getMaxConnections() {
         return Optional.ofNullable(getProperty(KEY_MAX_CONNECTIONS)).map(Integer::valueOf);

core/src/main/java/com/arangodb/internal/net/Communication.java

@@ -50,7 +50,9 @@ public CompletableFuture<InternalResponse> executeAsync(final InternalRequest re
 
     private CompletableFuture<InternalResponse> executeAsync(final InternalRequest request, final HostHandle hostHandle, final Host host, final int attemptCount) {
         long reqId = reqCount.getAndIncrement();
-        return doExecuteAsync(request, hostHandle, host, attemptCount, host.connection(), reqId);
+        return host.connection().thenCompose(c ->
+                doExecuteAsync(request, hostHandle, host, attemptCount, c, reqId)
+                        .whenComplete((r, t) -> c.release()));
     }
 
     private CompletableFuture<InternalResponse> doExecuteAsync(

core/src/main/java/com/arangodb/internal/net/Connection.java

@@ -35,4 +35,6 @@ public interface Connection extends Closeable {
     void setJwt(String jwt);
 
     CompletableFuture<InternalResponse> executeAsync(InternalRequest request);
+
+    void release();
 }

core/src/main/java/com/arangodb/internal/net/ConnectionFactory.java

@@ -29,5 +29,5 @@
  */
 @UsedInApi
 public interface ConnectionFactory {
-    Connection create(ArangoConfig config, HostDescription host);
+    Connection create(ArangoConfig config, HostDescription host, ConnectionPool pool);
 }

core/src/main/java/com/arangodb/internal/net/ConnectionPool.java

@@ -20,18 +20,22 @@
 
 package com.arangodb.internal.net;
 
-import com.arangodb.config.HostDescription;
+import com.arangodb.arch.UsedInApi;
 
 import java.io.Closeable;
+import java.util.concurrent.CompletableFuture;
 
 /**
  * @author Mark Vollmary
  */
+@UsedInApi
 public interface ConnectionPool extends Closeable {
 
-    Connection createConnection(final HostDescription host);
+    Connection createConnection();
 
-    Connection connection();
+    CompletableFuture<Connection> connection();
+
+    void release(final Connection connection);
 
     void setJwt(String jwt);