2 files changed, 29 insertions, 1 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/actions/cache/CompactPersistentActionCache.java b/src/main/java/com/google/devtools/build/lib/actions/cache/CompactPersistentActionCache.java
index a4406d7e43..3e608cf2da 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/cache/CompactPersistentActionCache.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/cache/CompactPersistentActionCache.java
@@ -281,7 +281,10 @@ public class CompactPersistentActionCache implements ActionCache {
   @Override
   public synchronized String toString() {
     StringBuilder builder = new StringBuilder();
-    builder.append("Action cache (" + map.size() + " records):\n");
+    // map.size() - 1 to avoid counting the validation key.
+    builder.append("Action cache (" + (map.size() - 1) + " records):\n");
+    int size = map.size() > 1000 ? 10 : map.size();
+    int ct = 0;
     for (Map.Entry<Integer, byte[]> entry: map.entrySet()) {
       if (entry.getKey() == VALIDATION_KEY) { continue; }
       String content;
@@ -292,6 +295,10 @@ public class CompactPersistentActionCache implements ActionCache {
       }
       builder.append("-> ").append(indexer.getStringForIndex(entry.getKey())).append("\n")
           .append(content).append("  packed_len = ").append(entry.getValue().length).append("\n");
+      if (++ct > size) {
+        builder.append("...");
+        break;
+      }
     }
     return builder.toString();
   }
diff --git a/src/test/java/com/google/devtools/build/lib/actions/cache/CompactPersistentActionCacheTest.java b/src/test/java/com/google/devtools/build/lib/actions/cache/CompactPersistentActionCacheTest.java
index 05b26fb9ec..d306327e80 100644
--- a/src/test/java/com/google/devtools/build/lib/actions/cache/CompactPersistentActionCacheTest.java
+++ b/src/test/java/com/google/devtools/build/lib/actions/cache/CompactPersistentActionCacheTest.java
@@ -14,6 +14,8 @@
 package com.google.devtools.build.lib.actions.cache;
 
 
+import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth.assertWithMessage;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
@@ -160,6 +162,25 @@ public class CompactPersistentActionCacheTest {
     entry.toString();
   }
 
+  private void assertToStringIsntTooBig(int numRecords) throws Exception {
+    for (int i = 0; i < numRecords; i++) {
+      putKey(Integer.toString(i));
+    }
+    String val = cache.toString();
+    assertThat(val).startsWith("Action cache (" + numRecords + " records):\n");
+    assertWithMessage(val).that(val.length()).isAtMost(2000);
+    // Cache was too big to print out fully.
+    if (numRecords > 10) {
+      assertThat(val).endsWith("...");
+    }
+  }
+
+  @Test
+  public void testToStringIsntTooBig() throws Exception {
+    assertToStringIsntTooBig(3);
+    assertToStringIsntTooBig(3000);
+  }
+
   private static void assertKeyEquals(ActionCache cache1, ActionCache cache2, String key) {
     Object entry = cache1.get(key);
     assertNotNull(entry);