diff --git a/staticlibs/Android.bp b/staticlibs/Android.bp
index ede6d3f..e2834b0 100644
--- a/staticlibs/Android.bp
+++ b/staticlibs/Android.bp
@@ -135,6 +135,7 @@
         "device/com/android/net/module/util/BpfUtils.java",
         "device/com/android/net/module/util/IBpfMap.java",
         "device/com/android/net/module/util/JniUtil.java",
+        "device/com/android/net/module/util/SingleWriterBpfMap.java",
         "device/com/android/net/module/util/TcUtils.java",
     ],
     sdk_version: "module_current",
diff --git a/staticlibs/device/com/android/net/module/util/SingleWriterBpfMap.java b/staticlibs/device/com/android/net/module/util/SingleWriterBpfMap.java
new file mode 100644
index 0000000..3eb59d8
--- /dev/null
+++ b/staticlibs/device/com/android/net/module/util/SingleWriterBpfMap.java
@@ -0,0 +1,129 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.net.module.util;
+
+import android.os.Build;
+import android.system.ErrnoException;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.RequiresApi;
+
+import java.util.HashMap;
+import java.util.NoSuchElementException;
+
+/**
+ * Subclass of BpfMap for maps that are only ever written by one userspace writer.
+ *
+ * This class stores all map data in a userspace HashMap in addition to in the BPF map. This makes
+ * reads (but not iterations) much faster because they do not require a system call or converting
+ * the raw map read to the Value struct. See, e.g., b/343166906 .
+ *
+ * Users of this class must ensure that no BPF program ever writes to the map, and that all
+ * userspace writes to the map occur through this object. Other userspace code may still read from
+ * the map; only writes are required to go through this object.
+ *
+ * Reads and writes to this object are thread-safe and internally synchronized. The read and write
+ * methods are synchronized to ensure that current writers always result in a consistent internal
+ * state (without synchronization, two concurrent writes might update the underlying map and the
+ * cache in the opposite order, resulting in the cache being out of sync with the map).
+ *
+ * getNextKey and iteration over the map are not synchronized or cached and always access the
+ * isunderlying map. The values returned by these calls may be temporarily out of sync with the
+ * values read and written through this object.
+ *
+ * TODO: consider caching reads on iterations as well. This is not trivial because the semantics for
+ * iterating BPF maps require passing in the previously-returned key, and Java iterators only
+ * support iterating from the beginning. It could be done by implementing forEach and possibly by
+ * making getFirstKey and getNextKey private (if no callers are using them). Because HashMap is not
+ * thread-safe, implementing forEach would require either making that method synchronized (and
+ * block reads and updates from other threads until iteration is complete) or switching the
+ * internal HashMap to ConcurrentHashMap.
+ *
+ * @param <K> the key of the map.
+ * @param <V> the value of the map.
+ */
+@RequiresApi(Build.VERSION_CODES.S)
+public class SingleWriterBpfMap<K extends Struct, V extends Struct> extends BpfMap<K, V> {
+    // HashMap instead of ArrayMap because it performs better on larger maps, and many maps used in
+    // our code can contain hundreds of items.
+    private final HashMap<K, V> mCache = new HashMap<>();
+
+    protected SingleWriterBpfMap(@NonNull final String path, final int flag, final Class<K> key,
+            final Class<V> value) throws ErrnoException, NullPointerException {
+        super(path, flag, key, value);
+
+        if (flag != BPF_F_RDWR) {
+            throw new IllegalArgumentException(
+                    "Using " + getClass().getName() + " for read-only maps does not make sense");
+        }
+
+        // Populate cache with the current map contents.
+        K currentKey = super.getFirstKey();
+        while (currentKey != null) {
+            mCache.put(currentKey, super.getValue(currentKey));
+            currentKey = super.getNextKey(currentKey);
+        }
+    }
+
+    public SingleWriterBpfMap(@NonNull final String path, final Class<K> key,
+            final Class<V> value) throws ErrnoException, NullPointerException {
+        this(path, BPF_F_RDWR, key, value);
+    }
+
+    @Override
+    public synchronized void updateEntry(K key, V value) throws ErrnoException {
+        super.updateEntry(key, value);
+        mCache.put(key, value);
+    }
+
+    @Override
+    public synchronized void insertEntry(K key, V value)
+            throws ErrnoException, IllegalStateException {
+        super.insertEntry(key, value);
+        mCache.put(key, value);
+    }
+
+    @Override
+    public synchronized void replaceEntry(K key, V value)
+            throws ErrnoException, NoSuchElementException {
+        super.replaceEntry(key, value);
+        mCache.put(key, value);
+    }
+
+    @Override
+    public synchronized boolean insertOrReplaceEntry(K key, V value) throws ErrnoException {
+        final boolean ret = super.insertOrReplaceEntry(key, value);
+        mCache.put(key, value);
+        return ret;
+    }
+
+    @Override
+    public synchronized boolean deleteEntry(K key) throws ErrnoException {
+        final boolean ret = super.deleteEntry(key);
+        mCache.remove(key);
+        return ret;
+    }
+
+    @Override
+    public synchronized boolean containsKey(@NonNull K key) throws ErrnoException {
+        return mCache.containsKey(key);
+    }
+
+    @Override
+    public synchronized V getValue(@NonNull K key) throws ErrnoException {
+        return mCache.get(key);
+    }
+}