From 5b77613ec628b22d72ac6fcd8239895c7ed8ae5c Mon Sep 17 00:00:00 2001
From: Ben Sidhom <sidhom@google.com>
Date: Tue, 27 Mar 2018 15:42:53 -0700
Subject: [PATCH] Use character replacement instead of regex for artifact
 flattening

---
 .../construction/ArtifactServiceStager.java   | 39 +++++++++----------
 1 file changed, 19 insertions(+), 20 deletions(-)

diff --git a/runners/core-construction-java/src/main/java/org/apache/beam/runners/core/construction/ArtifactServiceStager.java b/runners/core-construction-java/src/main/java/org/apache/beam/runners/core/construction/ArtifactServiceStager.java
index 58866f13e6482..ccda95c377fa1 100644
--- a/runners/core-construction-java/src/main/java/org/apache/beam/runners/core/construction/ArtifactServiceStager.java
+++ b/runners/core-construction-java/src/main/java/org/apache/beam/runners/core/construction/ArtifactServiceStager.java
@@ -18,11 +18,7 @@
 
 package org.apache.beam.runners.core.construction;
 
-import static com.google.common.base.Preconditions.checkState;
-
 import com.google.auto.value.AutoValue;
-import com.google.common.base.Preconditions;
-import com.google.common.collect.ImmutableMap;
 import com.google.common.io.BaseEncoding;
 import com.google.common.util.concurrent.ListeningExecutorService;
 import com.google.common.util.concurrent.MoreExecutors;
@@ -47,8 +43,6 @@
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executors;
 import java.util.concurrent.atomic.AtomicReference;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
 import javax.annotation.Nullable;
 import org.apache.beam.model.jobmanagement.v1.ArtifactApi.ArtifactChunk;
 import org.apache.beam.model.jobmanagement.v1.ArtifactApi.ArtifactMetadata;
@@ -67,13 +61,6 @@ public class ArtifactServiceStager {
   // 2 MB per file-request
   private static final int DEFAULT_BUFFER_SIZE = 2 * 1024 * 1024;
 
-  private static final Pattern PATH_ESCAPE_PATTERN = Pattern.compile("[_\\\\/.]");
-  private static final Map<String, String> PATH_ESCAPE_MAP = ImmutableMap.of(
-      "_", Matcher.quoteReplacement("__"),
-      "\\", Matcher.quoteReplacement("_."),
-      "/", Matcher.quoteReplacement("._"),
-      ".", Matcher.quoteReplacement(".."));
-
   public static ArtifactServiceStager overChannel(Channel channel) {
     return overChannel(channel, DEFAULT_BUFFER_SIZE);
   }
@@ -260,14 +247,26 @@ boolean isSuccess() {
   }
 
   private static String escapePath(String path) {
-    Matcher m = PATH_ESCAPE_PATTERN.matcher(path);
-    StringBuffer result = new StringBuffer();
-    while (m.find()) {
-      String replacement = PATH_ESCAPE_MAP.get(m.group());
-      checkState(replacement != null);
-      m.appendReplacement(result, replacement);
+    StringBuilder result = new StringBuilder(path.length() * 2);
+    for (int i = 0; i < path.length(); i++) {
+      char c = path.charAt(i);
+      switch (c) {
+        case '_':
+          result.append("__");
+          break;
+        case '\\':
+          result.append("_.");
+          break;
+        case '/':
+          result.append("._");
+          break;
+        case '.':
+          result.append("..");
+          break;
+        default:
+          result.append(c);
+      }
     }
-    m.appendTail(result);
     return result.toString();
   }
 }