From 80d90858ad98c4e274439a6fe628a4260a28cfdf Mon Sep 17 00:00:00 2001
From: Patrick Hiesel <hiesel@google.com>
Date: Fri, 28 Jan 2022 10:40:52 +0100
Subject: Memoize compiled RefPattern in ProjectCache

Compiling regular expressions is known to be expensive. If the access
section contains a regular expression, we pre compile and memoize it.

Release-Notes: Memoize reg-ex compilation in projects cache
Change-Id: I84f50323e9f08e69ab6414203927c7d2eacb23e4
(cherry picked from commit e235c42b099138f713ceef034923bfd7731f75ad)
---
 java/com/google/gerrit/entities/AccessSection.java       | 16 ++++++++++++++++
 .../google/gerrit/server/project/RefPatternMatcher.java  | 12 ++++++++++++
 .../com/google/gerrit/server/project/SectionMatcher.java |  2 +-
 3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/java/com/google/gerrit/entities/AccessSection.java b/java/com/google/gerrit/entities/AccessSection.java
index 69a234a5c4..8ae0a5dbed 100644
--- a/java/com/google/gerrit/entities/AccessSection.java
+++ b/java/com/google/gerrit/entities/AccessSection.java
@@ -18,12 +18,14 @@ import static com.google.common.collect.ImmutableList.toImmutableList;
 import static java.util.Objects.requireNonNull;
 
 import com.google.auto.value.AutoValue;
+import com.google.auto.value.extension.memoized.Memoized;
 import com.google.common.collect.ImmutableList;
 import com.google.gerrit.common.Nullable;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
 import java.util.function.Consumer;
+import java.util.regex.Pattern;
 
 /** Portion of a {@link Project} describing access rules. */
 @AutoValue
@@ -42,6 +44,20 @@ public abstract class AccessSection implements Comparable<AccessSection> {
   /** Name of the access section. It could be a ref pattern or something else. */
   public abstract String getName();
 
+  /**
+   * A compiled regular expression in case {@link #getName()} is a regular expression. This is
+   * memoized to save callers from compiling patterns for every use.
+   */
+  @Memoized
+  public Optional<Pattern> getNamePattern() {
+    if (isValidRefSectionName(getName())
+        && getName().startsWith(REGEX_PREFIX)
+        && !getName().contains("${")) {
+      return Optional.of(Pattern.compile(getName()));
+    }
+    return Optional.empty();
+  }
+
   public abstract ImmutableList<Permission> getPermissions();
 
   public static AccessSection create(String name) {
diff --git a/java/com/google/gerrit/server/project/RefPatternMatcher.java b/java/com/google/gerrit/server/project/RefPatternMatcher.java
index b9076b3db6..be840b5b23 100644
--- a/java/com/google/gerrit/server/project/RefPatternMatcher.java
+++ b/java/com/google/gerrit/server/project/RefPatternMatcher.java
@@ -22,6 +22,7 @@ import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Streams;
 import com.google.gerrit.common.data.ParameterizedString;
+import com.google.gerrit.entities.AccessSection;
 import com.google.gerrit.entities.Account;
 import com.google.gerrit.entities.RefNames;
 import com.google.gerrit.server.CurrentUser;
@@ -32,6 +33,13 @@ import java.util.regex.Pattern;
 import java.util.stream.Stream;
 
 public abstract class RefPatternMatcher {
+  public static RefPatternMatcher getMatcher(AccessSection section) {
+    if (section.getNamePattern().isPresent()) {
+      return new Regexp(section.getNamePattern().get());
+    }
+    return getMatcher(section.getName());
+  }
+
   public static RefPatternMatcher getMatcher(String pattern) {
     if (containsParameters(pattern)) {
       return new ExpandParameters(pattern);
@@ -79,6 +87,10 @@ public abstract class RefPatternMatcher {
       pattern = Pattern.compile(re);
     }
 
+    Regexp(Pattern re) {
+      pattern = re;
+    }
+
     @Override
     public boolean match(String ref, CurrentUser user) {
       return pattern.matcher(ref).matches() || (isRE(ref) && pattern.pattern().equals(ref));
diff --git a/java/com/google/gerrit/server/project/SectionMatcher.java b/java/com/google/gerrit/server/project/SectionMatcher.java
index 763957e03e..3d7175fa61 100644
--- a/java/com/google/gerrit/server/project/SectionMatcher.java
+++ b/java/com/google/gerrit/server/project/SectionMatcher.java
@@ -28,7 +28,7 @@ public class SectionMatcher extends RefPatternMatcher {
   static SectionMatcher wrap(Project.NameKey project, AccessSection section) {
     String ref = section.getName();
     if (AccessSection.isValidRefSectionName(ref)) {
-      return new SectionMatcher(project, section, getMatcher(ref));
+      return new SectionMatcher(project, section, getMatcher(section));
     }
     return null;
   }
-- 
cgit v1.2.3