[api] Moves NeuronUtils to api package (#2496)

api/src/main/java/ai/djl/util/NeuronUtils.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file except in compliance
+ * with the License. A copy of the License is located at
+ *
+ * http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file 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 ai.djl.util;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Iterator;
+import java.util.stream.Stream;
+
+/** A utility class to detect number of nueron cores. */
+public final class NeuronUtils {
+
+    private static final Logger logger = LoggerFactory.getLogger(NeuronUtils.class);
+
+    private NeuronUtils() {}
+
+    /**
+     * Returns whether Neuron runtime library is in the system.
+     *
+     * @return {@code true} if Neuron runtime library is in the system
+     */
+    public static boolean hasNeuron() {
+        return getNeuronCores() > 0;
+    }
+
+    /**
+     * Returns the number of NeuronCores available in the system.
+     *
+     * @return the number of NeuronCores available in the system
+     */
+    public static int getNeuronCores() {
+        return getNeuronCores("/sys/devices/virtual/neuron_device/");
+    }
+
+    @SuppressWarnings("PMD.ForLoopCanBeForeach")
+    static int getNeuronCores(String location) {
+        Path path = Paths.get(location);
+        if (!Files.exists(path)) {
+            return 0;
+        }
+        int count = 0;
+        try (Stream<Path> dev = Files.list(path)) {
+            for (Iterator<Path> it = dev.iterator(); it.hasNext(); ) {
+                Path dir = it.next();
+                if (dir.toFile().getName().startsWith("neuron")) {
+                    Stream<Path> cores = Files.list(dir);
+                    count += Math.toIntExact(cores.filter(NeuronUtils::matches).count());
+                    cores.close();
+                }
+            }
+        } catch (IOException e) {
+            logger.warn("Failed to list neuron cores", e);
+        }
+        return count;
+    }
+
+    private static boolean matches(Path p) {
+        return p.getFileName().toString().startsWith("neuron_core");
+    }
+}

api/src/test/java/ai/djl/util/NeuronUtilsTest.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file except in compliance
+ * with the License. A copy of the License is located at
+ *
+ * http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file 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 ai.djl.util;
+
+import org.testng.Assert;
+import org.testng.annotations.Test;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+public class NeuronUtilsTest {
+
+    @Test
+    public void testNeuronUtils() throws IOException {
+        Path dir = Paths.get("build/neuron_device/");
+        try {
+            for (int i = 0; i < 4; ++i) {
+                Path nd = dir.resolve("neuron" + i);
+                for (int j = 0; j < 2; ++j) {
+                    Path nc = nd.resolve("neuron_core" + j);
+                    Files.createDirectories(nc);
+                }
+            }
+            NeuronUtils.hasNeuron();
+            Assert.assertEquals(NeuronUtils.getNeuronCores(dir.toString()), 8);
+        } finally {
+            Utils.deleteQuietly(dir);
+        }
+    }
+}