1 files changed, 30 insertions, 6 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/serialization/strings/StringCodecs.java b/src/main/java/com/google/devtools/build/lib/skyframe/serialization/strings/StringCodecs.java
index 24f36ecb07..60e5f29f87 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/serialization/strings/StringCodecs.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/serialization/strings/StringCodecs.java
@@ -15,22 +15,46 @@
 package com.google.devtools.build.lib.skyframe.serialization.strings;
 
 import com.google.devtools.build.lib.skyframe.serialization.ObjectCodec;
+import java.util.logging.Logger;
 
 /** Utility for accessing (potentially platform-specific) {@link String} {@link ObjectCodec}s. */
 public final class StringCodecs {
 
-  private static final FastStringCodec fastStringCodec = new FastStringCodec();
-  private static final StringCodec stringCodec = new StringCodec();
+  private static final Logger logger = Logger.getLogger(StringCodecs.class.getName());
+
+  private static final StringCodec stringCodec;
+  private static final ObjectCodec<String> asciiOptimized;
+
+  static {
+    stringCodec = new StringCodec();
+    if (FastStringCodec.isAvailable()) {
+      asciiOptimized = new FastStringCodec();
+    } else {
+      logger.warning("Optimized string deserialization unavailable");
+      asciiOptimized = stringCodec;
+    }
+  }
 
   private StringCodecs() {}
 
   /**
-   * Returns singleton instance optimized for almost-always ASCII data. This instance can still
-   * serialize/deserialize UTF-8 data, but with potentially worse performance than
-   * {@link #simple()}.
+   * Returns whether or not optimized codecs are available. Exposed so users can check at runtime
+   * if the expected optimizations are applied.
+   */
+  public static boolean supportsOptimizedAscii() {
+    return asciiOptimized instanceof FastStringCodec;
+  }
+
+  /**
+   * Returns singleton instance optimized for almost-always ASCII data, if supported. Otherwise,
+   * returns a functional, but not optimized implementation. To tell if the optimized version is
+   * supported see {@link #supportsOptimizedAscii()}.
+   *
+   * <p>Note that when optimized, this instance can still serialize/deserialize UTF-8 data, but with
+   *  potentially worse performance than {@link #simple()}.
    */
   public static ObjectCodec<String> asciiOptimized() {
-    return fastStringCodec;
+    return asciiOptimized;
   }
 
   /**