Introduce HTTP content encoding H1 & H2 (#1174)

* Introduce HTTP content encoding H1 & H2

Motivation:

Our HTTP clients & servers don't support any form of compression. There are many use cases that involve large payloads, that compression could make a difference on the HTTP timings.

Modifications:

H1 & H2 protocols were altered to support a list of supported-encodings. We provide the default ones out of the box as part of the discoverability helper ContentEncodings, which offers, GZIP & DEFLATE.
To keep the behavior consistent between the two protocols, we chose to communicate the compression technique to the relevant endpoints through the 'Content-Encoding & Accept-Content-Encoding' headers, rather than on the 'Transfer-Encoding & TE' headers, which are not supported by H2.

Result:

Once the client & server are configured to support different encodings through the new filters (`ContentCodingHttpRequesterFilter` and `ContentCodingHttpServiceFilter`), the server will decide on the encoding based on the client's advertised headers. To disable the encoding for a particular request, or enforce a specific encoding, one can call response.encoding(...) to do so. That, bypasses the auto-selection, and also ignores compatibility checks with the client.

Encoding & Decoding is done in a streaming fashion.

servicetalk-buffer-api/src/main/java/io/servicetalk/buffer/api/BufferAllocator.java

@@ -50,6 +50,15 @@ default Buffer newBuffer(boolean direct) {
      */
     Buffer newBuffer(int initialCapacity);
 
+    /**
+     * Create a new buffer with the given initial capacity and given max capacity.
+     *
+     * @param initialCapacity the initial capacity of the buffer.
+     * @param maxCapacity the maximum capacity of the buffer.
+     * @return a new buffer.
+     */
+    Buffer newBuffer(int initialCapacity, int maxCapacity);
+
     /**
      * Create a new buffer with the given initial capacity.
      *

servicetalk-buffer-api/src/main/java/io/servicetalk/buffer/api/ReadOnlyBufferAllocator.java

@@ -45,6 +45,11 @@ public Buffer newBuffer(int initialCapacity) {
         throw new UnsupportedOperationException();
     }
 
+    @Override
+    public Buffer newBuffer(final int initialCapacity, final int maxCapacity) {
+        throw new UnsupportedOperationException();
+    }
+
     @Override
     public Buffer newBuffer(int initialCapacity, boolean direct) {
         throw new UnsupportedOperationException();

servicetalk-buffer-netty/src/main/java/io/servicetalk/buffer/netty/ServiceTalkBufferAllocator.java

@@ -133,6 +133,11 @@ public Buffer newBuffer(int initialCapacity) {
         return new NettyBuffer<>(buffer(initialCapacity));
     }
 
+    @Override
+    public Buffer newBuffer(final int initialCapacity, final int maxCapacity) {
+        return new NettyBuffer<>(buffer(initialCapacity, maxCapacity));
+    }
+
     @Override
     public Buffer newBuffer(int initialCapacity, boolean direct) {
         return new NettyBuffer<>(direct ? directBuffer(initialCapacity) : heapBuffer(initialCapacity));

servicetalk-encoding-api/build.gradle

@@ -0,0 +1,27 @@
+/*
+ * Copyright © 2020 Apple Inc. and the ServiceTalk project 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.
+ */
+
+apply plugin: "io.servicetalk.servicetalk-gradle-plugin-internal-library"
+
+dependencies {
+    api project(":servicetalk-buffer-api")
+    api project(":servicetalk-concurrent-api")
+
+    implementation project(":servicetalk-annotations")
+    implementation project(":servicetalk-concurrent-internal")
+    implementation "com.google.code.findbugs:jsr305:$jsr305Version"
+    implementation "org.slf4j:slf4j-api:$slf4jVersion"
+}

servicetalk-encoding-api/src/main/java/io/servicetalk/encoding/api/AbstractContentCodec.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright © 2020 Apple Inc. and the ServiceTalk project 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 io.servicetalk.encoding.api;
+
+import java.util.Objects;
+
+abstract class AbstractContentCodec implements ContentCodec {
+
+    private final CharSequence name;
+
+    AbstractContentCodec(final CharSequence name) {
+        this.name = name;
+    }
+
+    public final CharSequence name() {
+        return name;
+    }
+
+    @Override
+    public boolean equals(final Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        final AbstractContentCodec that = (AbstractContentCodec) o;
+        return name.equals(that.name);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(name);
+    }
+
+    @Override
+    public String toString() {
+        return "ContentCodec{" +
+                "name=" + name +
+                '}';
+    }
+}