Added support to read single parquet file hosted in AWS S3

Util/channel/build.gradle

@@ -0,0 +1,22 @@
+plugins {
+    id 'java-library'
+    id 'io.deephaven.project.register'
+}
+
+dependencies {
+    implementation project(':Base')
+
+    // Needed for SafeCloseable
+    implementation project(':Util')
+
+    compileOnly depAnnotations
+
+    Classpaths.inheritJUnitPlatform(project)
+    Classpaths.inheritAssertJ(project)
+    testImplementation 'org.junit.jupiter:junit-jupiter'
+    testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine'
+}
+
+test {
+    useJUnitPlatform()
+}

Util/channel/gradle.properties

@@ -0,0 +1 @@
+io.deephaven.project.ProjectType=JAVA_PUBLIC

extensions/parquet/base/src/main/java/io/deephaven/parquet/base/util/CachedChannelProvider.java → Util/channel/src/main/java/io/deephaven/util/channel/CachedChannelProvider.java

@@ -1,17 +1,19 @@
 /**
  * Copyright (c) 2016-2022 Deephaven Data Labs and Patent Pending
  */
-package io.deephaven.parquet.base.util;
+package io.deephaven.util.channel;
 
 import io.deephaven.base.RAPriQueue;
 import io.deephaven.base.verify.Assert;
 import io.deephaven.base.verify.Require;
 import io.deephaven.hash.KeyedObjectHashMap;
 import io.deephaven.hash.KeyedObjectKey;
+import io.deephaven.util.annotations.FinalDefault;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.io.IOException;
+import java.net.URI;
 import java.nio.ByteBuffer;
 import java.nio.channels.SeekableByteChannel;
 import java.nio.file.Path;
@@ -22,6 +24,15 @@
  */
 public class CachedChannelProvider implements SeekableChannelsProvider {
 
+    public interface ContextHolder {
+        void setContext(SeekableChannelContext channelContext);
+
+        @FinalDefault
+        default void clearContext() {
+            setContext(null);
+        }
+    }
+
     private final SeekableChannelsProvider wrappedProvider;
     private final int maximumPooledCount;
 
@@ -52,13 +63,27 @@ public CachedChannelProvider(@NotNull final SeekableChannelsProvider wrappedProv
     }
 
     @Override
-    public SeekableByteChannel getReadChannel(@NotNull final Path path) throws IOException {
-        final String pathKey = path.toAbsolutePath().toString();
+    public SeekableChannelContext makeContext() {
+        return wrappedProvider.makeContext();
+    }
+
+    @Override
+    public boolean isCompatibleWith(@NotNull final SeekableChannelContext channelContext) {
+        return wrappedProvider.isCompatibleWith(channelContext);
+    }
+
+    @Override
+    public SeekableByteChannel getReadChannel(@NotNull final SeekableChannelContext channelContext,
+            @NotNull final URI uri)
+            throws IOException {
+        final String uriString = uri.toString();
         final KeyedObjectHashMap<String, PerPathPool> channelPool = channelPools.get(ChannelType.Read);
-        final CachedChannel result = tryGetPooledChannel(pathKey, channelPool);
-        return result == null
-                ? new CachedChannel(wrappedProvider.getReadChannel(path), ChannelType.Read, pathKey)
+        final CachedChannel result = tryGetPooledChannel(uriString, channelPool);
+        final CachedChannel channel = result == null
+                ? new CachedChannel(wrappedProvider.getReadChannel(channelContext, uri), ChannelType.Read, uriString)
                 : result.position(0);
+        channel.setContext(channelContext);
+        return channel;
     }
 
     @Override
@@ -125,10 +150,15 @@ private long advanceClock() {
         return logicalClock = 1;
     }
 
+    @Override
+    public void close() {
+        wrappedProvider.close();
+    }
+
     /**
      * {@link SeekableByteChannel Channel} wrapper for pooled usage.
      */
-    private class CachedChannel implements SeekableByteChannel {
+    private class CachedChannel implements SeekableByteChannel, ContextHolder {
 
         private final SeekableByteChannel wrappedChannel;
         private final ChannelType channelType;
@@ -163,7 +193,7 @@ public long position() throws IOException {
         }
 
         @Override
-        public SeekableByteChannel position(final long newPosition) throws IOException {
+        public CachedChannel position(final long newPosition) throws IOException {
             Require.eqTrue(isOpen, "isOpen");
             wrappedChannel.position(newPosition);
             return this;
@@ -196,12 +226,20 @@ public boolean isOpen() {
         public void close() throws IOException {
             Require.eqTrue(isOpen, "isOpen");
             isOpen = false;
+            clearContext();
             returnPoolableChannel(this);
         }
 
         private void dispose() throws IOException {
             wrappedChannel.close();
         }
+
+        @Override
+        public final void setContext(@Nullable final SeekableChannelContext channelContext) {
+            if (wrappedChannel instanceof ContextHolder) {
+                ((ContextHolder) wrappedChannel).setContext(channelContext);
+            }
+        }
     }
 
     /**

extensions/parquet/base/src/main/java/io/deephaven/parquet/base/util/LocalFSChannelProvider.java → Util/channel/src/main/java/io/deephaven/util/channel/LocalFSChannelProvider.java

@@ -1,11 +1,13 @@
 /**
  * Copyright (c) 2016-2022 Deephaven Data Labs and Patent Pending
  */
-package io.deephaven.parquet.base.util;
+package io.deephaven.util.channel;
 
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.io.IOException;
+import java.net.URI;
 import java.nio.channels.FileChannel;
 import java.nio.channels.SeekableByteChannel;
 import java.nio.file.Path;
@@ -14,8 +16,23 @@
 public class LocalFSChannelProvider implements SeekableChannelsProvider {
 
     @Override
-    public SeekableByteChannel getReadChannel(@NotNull final Path path) throws IOException {
-        return FileChannel.open(path, StandardOpenOption.READ);
+    public SeekableChannelContext makeContext() {
+        // No additional context required for local FS
+        return SeekableChannelContext.NULL;
+    }
+
+    @Override
+    public boolean isCompatibleWith(@Nullable final SeekableChannelContext channelContext) {
+        // Context is not used, hence always compatible
+        return true;
+    }
+
+    @Override
+    public SeekableByteChannel getReadChannel(@Nullable final SeekableChannelContext channelContext,
+            @NotNull final URI uri)
+            throws IOException {
+        // context is unused here
+        return FileChannel.open(Path.of(uri), StandardOpenOption.READ);
     }
 
     @Override
@@ -31,4 +48,7 @@ public SeekableByteChannel getWriteChannel(@NotNull final Path filePath, final b
         }
         return result;
     }
+
+    @Override
+    public void close() {}
 }

Util/channel/src/main/java/io/deephaven/util/channel/SeekableChannelContext.java

@@ -0,0 +1,16 @@
+package io.deephaven.util.channel;
+
+import io.deephaven.util.SafeCloseable;
+
+/**
+ * Context object for reading and writing to channels created by {@link SeekableChannelsProvider}.
+ */
+public interface SeekableChannelContext extends SafeCloseable {
+
+    SeekableChannelContext NULL = new SeekableChannelContext() {};
+
+    /**
+     * Release any resources associated with this context. The context should not be used afterward.
+     */
+    default void close() {}
+}

Util/channel/src/main/java/io/deephaven/util/channel/SeekableChannelsProvider.java

@@ -0,0 +1,64 @@
+/**
+ * Copyright (c) 2016-2022 Deephaven Data Labs and Patent Pending
+ */
+package io.deephaven.util.channel;
+
+import io.deephaven.util.SafeCloseable;
+import org.jetbrains.annotations.NotNull;
+
+import java.io.File;
+import java.io.IOException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.nio.channels.SeekableByteChannel;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+public interface SeekableChannelsProvider extends SafeCloseable {
+
+    /**
+     * Take the file source path or URI and convert it to a URI object.
+     *
+     * @param source The file source path or URI
+     * @return The URI object
+     */
+    static URI convertToURI(final String source) {
+        final URI uri;
+        try {
+            uri = new URI(source);
+        } catch (final URISyntaxException e) {
+            // If the URI is invalid, assume it's a file path
+            return new File(source).toURI();
+        }
+        if (uri.getScheme() == null) {
+            // Need to convert to a "file" URI
+            return new File(source).toURI();
+        }
+        return uri;
+    }
+
+    /**
+     * Create a new {@link SeekableChannelContext} object for creating read channels via this provider.
+     */
+    SeekableChannelContext makeContext();
+
+    /**
+     * Check if the given context is compatible with this provider. Useful to test if we can use provided
+     * {@code context} object for creating channels with this provider.
+     */
+    boolean isCompatibleWith(@NotNull SeekableChannelContext channelContext);
+
+    default SeekableByteChannel getReadChannel(@NotNull SeekableChannelContext channelContext, @NotNull String uriStr)
+            throws IOException {
+        return getReadChannel(channelContext, convertToURI(uriStr));
+    }
+
+    SeekableByteChannel getReadChannel(@NotNull SeekableChannelContext channelContext, @NotNull URI uri)
+            throws IOException;
+
+    default SeekableByteChannel getWriteChannel(@NotNull final String path, final boolean append) throws IOException {
+        return getWriteChannel(Paths.get(path), append);
+    }
+
+    SeekableByteChannel getWriteChannel(@NotNull Path path, boolean append) throws IOException;
+}

Util/channel/src/main/java/io/deephaven/util/channel/SeekableChannelsProviderLoader.java

@@ -0,0 +1,56 @@
+/**
+ * Copyright (c) 2016-2022 Deephaven Data Labs and Patent Pending
+ */
+package io.deephaven.util.channel;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.net.URI;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.ServiceLoader;
+
+/**
+ * A service loader class for loading {@link SeekableChannelsProviderPlugin} implementations at runtime and provide
+ * {@link SeekableChannelsProvider} implementations for different URI schemes, e.g., S3.
+ */
+public final class SeekableChannelsProviderLoader {
+
+    private static volatile SeekableChannelsProviderLoader instance;
+
+    public static SeekableChannelsProviderLoader getInstance() {
+        if (instance == null) {
+            instance = new SeekableChannelsProviderLoader();
+        }
+        return instance;
+    }
+
+    private final List<SeekableChannelsProviderPlugin> providers;
+
+    private SeekableChannelsProviderLoader() {
+        providers = new ArrayList<>();
+        // Load the plugins
+        for (final SeekableChannelsProviderPlugin plugin : ServiceLoader.load(SeekableChannelsProviderPlugin.class)) {
+            providers.add(plugin);
+        }
+    }
+
+    /**
+     * Create a new {@link SeekableChannelsProvider} based on given URI and object using the plugins loaded by the
+     * {@link ServiceLoader}. For example, for a "S3" URI, we will create a {@link SeekableChannelsProvider} which can
+     * read files from S3.
+     *
+     * @param uri The URI
+     * @param object An optional object to pass to the {@link SeekableChannelsProviderPlugin} implementations.
+     * @return A {@link SeekableChannelsProvider} for the given URI.
+     */
+    public SeekableChannelsProvider fromServiceLoader(@NotNull final URI uri, @Nullable final Object object) {
+        for (final SeekableChannelsProviderPlugin plugin : providers) {
+            if (plugin.isCompatible(uri, object)) {
+                return plugin.createProvider(uri, object);
+            }
+        }
+        throw new UnsupportedOperationException("No plugin found for uri: " + uri);
+    }
+}

Util/channel/src/main/java/io/deephaven/util/channel/SeekableChannelsProviderPlugin.java

@@ -0,0 +1,25 @@
+/**
+ * Copyright (c) 2016-2022 Deephaven Data Labs and Patent Pending
+ */
+package io.deephaven.util.channel;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.net.URI;
+
+/**
+ * A plugin interface for providing {@link SeekableChannelsProvider} implementations for different URI schemes, e.g. S3.
+ * Check out {@link SeekableChannelsProviderLoader} for more details.
+ */
+public interface SeekableChannelsProviderPlugin {
+    /**
+     * Check if this plugin is compatible with the given URI and config object.
+     */
+    boolean isCompatible(@NotNull URI uri, @Nullable Object config);
+
+    /**
+     * Create a {@link SeekableChannelsProvider} for the given URI and config object.
+     */
+    SeekableChannelsProvider createProvider(@NotNull URI uri, @Nullable Object object);
+}