feat: Add a builder to handle the common logic of extracting routing …

…header values from request (#1598) In order to support explicit dynamic routing headers, we have to match-and-extract field values from requests during runtime for each configured routing rule parameter, this PR is to add a request params builder to handle the common logics.
googleapis · Jan 27, 2022 · 2836baa · 2836baa
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diff --git a/gax/src/main/java/com/google/api/gax/rpc/RequestParamsBuilder.java b/gax/src/main/java/com/google/api/gax/rpc/RequestParamsBuilder.java
@@ -0,0 +1,78 @@
+/*
+ * Copyright 2022 Google LLC
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google LLC nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package com.google.api.gax.rpc;
+
+import com.google.api.core.BetaApi;
+import com.google.api.pathtemplate.PathTemplate;
+import com.google.common.collect.ImmutableMap;
+import java.util.Map;
+
+/**
+ * This builder class builds a request params map that will be used by autogenerated implementation
+ * of {@link RequestParamsExtractor}.
+ */
+@BetaApi
+public class RequestParamsBuilder {
+
+  private final ImmutableMap.Builder<String, String> paramsBuilder;
+
+  private RequestParamsBuilder() {
+    this.paramsBuilder = ImmutableMap.builder();
+  }
+
+  public static RequestParamsBuilder create() {
+    return new RequestParamsBuilder();
+  }
+
+  /**
+   * Add an entry to paramsBuilder by match-and-extract field values from requests based on
+   * pre-configured path templates. This method is called repeatedly for each configured routing
+   * rule parameter, it's possible that the incoming field value from request is null or there is no
+   * matches found, we'll continue the match-and-extract process for the next routing rule parameter
+   * in such case.
+   *
+   * @param fieldValue the field value from a request
+   * @param headerKey the header key for the routing header param
+   * @param pathTemplate {@link PathTemplate} the path template used for match-and-extract
+   */
+  public void add(String fieldValue, String headerKey, PathTemplate pathTemplate) {
+    if (fieldValue == null) {
+      return;
+    }
+    Map<String, String> matchedValues = pathTemplate.match(fieldValue);
+    if (matchedValues != null && matchedValues.containsKey(headerKey)) {
+      paramsBuilder.put(headerKey, matchedValues.get(headerKey));
+    }
+  }
+
+  public Map<String, String> build() {
+    return paramsBuilder.build();
+  }
+}
diff --git a/gax/src/test/java/com/google/api/gax/rpc/RequestParamsBuilderTest.java b/gax/src/test/java/com/google/api/gax/rpc/RequestParamsBuilderTest.java
@@ -0,0 +1,92 @@
+/*
+ * Copyright 2022 Google LLC
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google LLC nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package com.google.api.gax.rpc;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.api.pathtemplate.PathTemplate;
+import java.util.Map;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public class RequestParamsBuilderTest {
+
+  private RequestParamsBuilder requestParamsBuilder;
+
+  @Before
+  public void setUp() {
+    requestParamsBuilder = RequestParamsBuilder.create();
+  }
+
+  @Test
+  public void add_happyPath() {
+    String headerKey = "table_location";
+    Map<String, String> actual =
+        getRoutingHeaders(
+            headerKey,
+            "projects/**/{table_location=instances/*}",
+            "projects/my_cozy_home/instances/living_room");
+    assertThat(actual).containsExactly(headerKey, "instances/living_room");
+  }
+
+  @Test
+  public void add_matchedValuesWithNoRoutingHeaderKey() {
+    Map<String, String> actual =
+        getRoutingHeaders("table_location", "projects/**", "projects/my_cozy_home/");
+    assertThat(actual).isEmpty();
+  }
+
+  @Test
+  public void add_emptyMatchedValues() {
+    Map<String, String> actual =
+        getRoutingHeaders(
+            "table_location",
+            "projects/**/{table_location=instances/*}",
+            "projects/does_not_matter");
+    assertThat(actual).isEmpty();
+  }
+
+  @Test
+  public void add_nullFieldValue() {
+    Map<String, String> actual = getRoutingHeaders("table_location", "projects/**", null);
+    assertThat(actual).isEmpty();
+  }
+
+  private Map<String, String> getRoutingHeaders(
+      String headerKey, String patternString, String fieldValue) {
+    PathTemplate pathTemplate = PathTemplate.create(patternString);
+    requestParamsBuilder.add(fieldValue, headerKey, pathTemplate);
+    return requestParamsBuilder.build();
+  }
+}