checkstyle: enforce static import from Preconditions (#455)

A spiritual backport of apache/beam#1030

Author: dhalperi

checkstyle.xml

@@ -141,6 +141,12 @@ page at http://checkstyle.sourceforge.net/config.html -->
       <property name="format" value="com\.google\.api\.client\.util\.(ByteStreams|Charsets|Collections2|Joiner|Lists|Maps|Objects|Preconditions|Sets|Strings|Throwables)"/>
     </module>
 
+    <!-- Require static importing from Preconditions. -->
+    <module name="RegexpSinglelineJava">
+      <property name="format" value="^import com.google.common.base.Preconditions;$"/>
+      <property name="message" value="Static import functions from Guava Preconditions"/>
+    </module>
+
     <module name="UnusedImports">
       <property name="severity" value="error"/>
       <property name="processJavadoc" value="true"/>

contrib/firebaseio/src/main/java/com/google/cloud/dataflow/contrib/firebase/io/FirebaseSource.java

@@ -15,6 +15,8 @@
  */
 package com.google.cloud.dataflow.contrib.firebase.io;
 
+import static com.google.common.base.Preconditions.checkNotNull;
+
 import com.google.cloud.dataflow.contrib.firebase.events.ChildAdded;
 import com.google.cloud.dataflow.contrib.firebase.events.ChildChanged;
 import com.google.cloud.dataflow.contrib.firebase.events.ChildMoved;
@@ -33,8 +35,6 @@
 import com.google.cloud.dataflow.sdk.options.PipelineOptions;
 import com.google.cloud.dataflow.sdk.values.TypeDescriptor;
 
-import com.google.common.base.Preconditions;
-
 import com.fasterxml.jackson.databind.ObjectWriter;
 import com.firebase.client.AuthData;
 import com.firebase.client.ChildEventListener;
@@ -389,7 +389,7 @@ public void validate() {
       Thread.currentThread().interrupt();
       throw new RuntimeException("Thread interrupted while waiting for authentication to complete", e);
     }
-    Preconditions.checkNotNull(result, "If result is null, authenticators is ");
+    checkNotNull(result, "If result is null, authenticators is ");
   }
 
   @Override

contrib/hadoop/src/main/java/com/google/cloud/dataflow/contrib/hadoop/HadoopFileSource.java

@@ -16,6 +16,9 @@
 
 package com.google.cloud.dataflow.contrib.hadoop;
 
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkNotNull;
+
 import com.google.cloud.dataflow.sdk.coders.Coder;
 import com.google.cloud.dataflow.sdk.coders.KvCoder;
 import com.google.cloud.dataflow.sdk.coders.VoidCoder;
@@ -24,7 +27,6 @@
 import com.google.cloud.dataflow.sdk.options.PipelineOptions;
 import com.google.cloud.dataflow.sdk.values.KV;
 import com.google.common.base.Function;
-import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Lists;
 import org.apache.hadoop.conf.Configuration;
@@ -164,14 +166,10 @@ public Class<V> getValueClass() {
 
   @Override
   public void validate() {
-    Preconditions.checkNotNull(filepattern,
-        "need to set the filepattern of a HadoopFileSource");
-    Preconditions.checkNotNull(formatClass,
-        "need to set the format class of a HadoopFileSource");
-    Preconditions.checkNotNull(keyClass,
-        "need to set the key class of a HadoopFileSource");
-    Preconditions.checkNotNull(valueClass,
-        "need to set the value class of a HadoopFileSource");
+    checkNotNull(filepattern, "need to set the filepattern of a HadoopFileSource");
+    checkNotNull(formatClass, "need to set the format class of a HadoopFileSource");
+    checkNotNull(keyClass, "need to set the key class of a HadoopFileSource");
+    checkNotNull(valueClass, "need to set the value class of a HadoopFileSource");
   }
 
   @Override
@@ -466,8 +464,7 @@ public SerializableSplit() {
     }
 
     public SerializableSplit(InputSplit split) {
-      Preconditions.checkArgument(split instanceof Writable, "Split is not writable: "
-          + split);
+      checkArgument(split instanceof Writable, "Split is not writable: %s", split);
       this.split = split;
     }
 

contrib/join-library/src/main/java/com/google/cloud/dataflow/contrib/joinlibrary/Join.java

@@ -16,6 +16,8 @@
 
 package com.google.cloud.dataflow.contrib.joinlibrary;
 
+import static com.google.common.base.Preconditions.checkNotNull;
+
 import com.google.cloud.dataflow.sdk.coders.KvCoder;
 import com.google.cloud.dataflow.sdk.transforms.DoFn;
 import com.google.cloud.dataflow.sdk.transforms.ParDo;
@@ -25,7 +27,6 @@
 import com.google.cloud.dataflow.sdk.values.KV;
 import com.google.cloud.dataflow.sdk.values.PCollection;
 import com.google.cloud.dataflow.sdk.values.TupleTag;
-import com.google.common.base.Preconditions;
 
 /**
  * Utility class with different versions of joins. All methods join two collections of
@@ -45,8 +46,8 @@ public class Join {
    */
   public static <K, V1, V2> PCollection<KV<K, KV<V1, V2>>> innerJoin(
     final PCollection<KV<K, V1>> leftCollection, final PCollection<KV<K, V2>> rightCollection) {
-    Preconditions.checkNotNull(leftCollection);
-    Preconditions.checkNotNull(rightCollection);
+    checkNotNull(leftCollection);
+    checkNotNull(rightCollection);
 
     final TupleTag<V1> v1Tuple = new TupleTag<>();
     final TupleTag<V2> v2Tuple = new TupleTag<>();
@@ -93,9 +94,9 @@ public static <K, V1, V2> PCollection<KV<K, KV<V1, V2>>> leftOuterJoin(
     final PCollection<KV<K, V1>> leftCollection,
     final PCollection<KV<K, V2>> rightCollection,
     final V2 nullValue) {
-    Preconditions.checkNotNull(leftCollection);
-    Preconditions.checkNotNull(rightCollection);
-    Preconditions.checkNotNull(nullValue);
+    checkNotNull(leftCollection);
+    checkNotNull(rightCollection);
+    checkNotNull(nullValue);
 
     final TupleTag<V1> v1Tuple = new TupleTag<>();
     final TupleTag<V2> v2Tuple = new TupleTag<>();
@@ -146,9 +147,9 @@ public static <K, V1, V2> PCollection<KV<K, KV<V1, V2>>> rightOuterJoin(
     final PCollection<KV<K, V1>> leftCollection,
     final PCollection<KV<K, V2>> rightCollection,
     final V1 nullValue) {
-    Preconditions.checkNotNull(leftCollection);
-    Preconditions.checkNotNull(rightCollection);
-    Preconditions.checkNotNull(nullValue);
+    checkNotNull(leftCollection);
+    checkNotNull(rightCollection);
+    checkNotNull(nullValue);
 
     final TupleTag<V1> v1Tuple = new TupleTag<>();
     final TupleTag<V2> v2Tuple = new TupleTag<>();

sdk/src/main/java/com/google/cloud/dataflow/sdk/io/CompressedSource.java

@@ -16,17 +16,17 @@
 
 package com.google.cloud.dataflow.sdk.io;
 
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkNotNull;
+
 import com.google.cloud.dataflow.sdk.annotations.Experimental;
 import com.google.cloud.dataflow.sdk.coders.Coder;
 import com.google.cloud.dataflow.sdk.options.PipelineOptions;
 import com.google.cloud.dataflow.sdk.transforms.display.DisplayData;
-import com.google.common.base.Preconditions;
 import com.google.common.io.ByteStreams;
 import com.google.common.primitives.Ints;
-
 import org.apache.commons.compress.compressors.bzip2.BZip2CompressorInputStream;
 import org.apache.commons.compress.compressors.gzip.GzipCompressorInputStream;
-
 import java.io.IOException;
 import java.io.PushbackInputStream;
 import java.io.Serializable;
@@ -35,7 +35,6 @@
 import java.nio.channels.ReadableByteChannel;
 import java.util.NoSuchElementException;
 import java.util.zip.GZIPInputStream;
-
 import javax.annotation.concurrent.GuardedBy;
 
 /**
@@ -253,7 +252,7 @@ private CompressedSource(FileBasedSource<T> sourceDelegate,
     this.sourceDelegate = sourceDelegate;
     this.channelFactory = channelFactory;
     try {
-      Preconditions.checkArgument(
+      checkArgument(
           isSplittable() || startOffset == 0,
           "CompressedSources must start reading at offset 0. Requested offset: " + startOffset);
     } catch (Exception e) {
@@ -268,9 +267,9 @@ private CompressedSource(FileBasedSource<T> sourceDelegate,
   @Override
   public void validate() {
     super.validate();
-    Preconditions.checkNotNull(sourceDelegate);
+    checkNotNull(sourceDelegate);
     sourceDelegate.validate();
-    Preconditions.checkNotNull(channelFactory);
+    checkNotNull(channelFactory);
   }
 
   /**

sdk/src/main/java/com/google/cloud/dataflow/sdk/io/FileBasedSource.java

@@ -14,22 +14,22 @@
 
 package com.google.cloud.dataflow.sdk.io;
 
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkState;
+
 import com.google.cloud.dataflow.sdk.options.PipelineOptions;
 import com.google.cloud.dataflow.sdk.transforms.display.DisplayData;
 import com.google.cloud.dataflow.sdk.util.IOChannelFactory;
 import com.google.cloud.dataflow.sdk.util.IOChannelUtils;
-import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
 import com.google.common.util.concurrent.Futures;
 import com.google.common.util.concurrent.ListenableFuture;
 import com.google.common.util.concurrent.ListeningExecutorService;
 import com.google.common.util.concurrent.MoreExecutors;
-
 import org.joda.time.Instant;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
-
 import java.io.IOException;
 import java.nio.channels.ReadableByteChannel;
 import java.nio.channels.SeekableByteChannel;
@@ -133,18 +133,18 @@ public final Mode getMode() {
 
   @Override
   public final FileBasedSource<T> createSourceForSubrange(long start, long end) {
-    Preconditions.checkArgument(mode != Mode.FILEPATTERN,
+    checkArgument(mode != Mode.FILEPATTERN,
         "Cannot split a file pattern based source based on positions");
-    Preconditions.checkArgument(start >= getStartOffset(), "Start offset value " + start
+    checkArgument(start >= getStartOffset(), "Start offset value " + start
         + " of the subrange cannot be smaller than the start offset value " + getStartOffset()
         + " of the parent source");
-    Preconditions.checkArgument(end <= getEndOffset(), "End offset value " + end
+    checkArgument(end <= getEndOffset(), "End offset value " + end
         + " of the subrange cannot be larger than the end offset value " + getEndOffset()
         + " of the parent source");
 
     FileBasedSource<T> source = createForSubrangeOfFile(fileOrPatternSpec, start, end);
     if (start > 0 || end != Long.MAX_VALUE) {
-      Preconditions.checkArgument(source.getMode() == Mode.SINGLE_FILE_OR_SUBRANGE,
+      checkArgument(source.getMode() == Mode.SINGLE_FILE_OR_SUBRANGE,
           "Source created for the range [" + start + "," + end + ")"
           + " must be a subrange source");
     }
@@ -386,10 +386,10 @@ public void validate() {
     super.validate();
     switch (mode) {
       case FILEPATTERN:
-        Preconditions.checkArgument(getStartOffset() == 0,
+        checkArgument(getStartOffset() == 0,
             "FileBasedSource is based on a file pattern or a full single file "
             + "but the starting offset proposed " + getStartOffset() + " is not zero");
-        Preconditions.checkArgument(getEndOffset() == Long.MAX_VALUE,
+        checkArgument(getEndOffset() == Long.MAX_VALUE,
             "FileBasedSource is based on a file pattern or a full single file "
             + "but the ending offset proposed " + getEndOffset() + " is not Long.MAX_VALUE");
         break;
@@ -468,7 +468,7 @@ public abstract static class FileBasedReader<T> extends OffsetBasedReader<T> {
      */
     public FileBasedReader(FileBasedSource<T> source) {
       super(source);
-      Preconditions.checkArgument(source.getMode() != Mode.FILEPATTERN,
+      checkArgument(source.getMode() != Mode.FILEPATTERN,
           "FileBasedReader does not support reading file patterns");
     }
 
@@ -488,10 +488,10 @@ protected final boolean startImpl() throws IOException {
         seekChannel.position(source.getStartOffset());
       } else {
         // Channel is not seekable. Must not be a subrange.
-        Preconditions.checkArgument(source.mode != Mode.SINGLE_FILE_OR_SUBRANGE,
+        checkArgument(source.mode != Mode.SINGLE_FILE_OR_SUBRANGE,
             "Subrange-based sources must only be defined for file types that support seekable "
             + " read channels");
-        Preconditions.checkArgument(source.getStartOffset() == 0, "Start offset "
+        checkArgument(source.getStartOffset() == 0, "Start offset "
             + source.getStartOffset()
             + " is not zero but channel for reading the file is not seekable.");
       }
@@ -574,7 +574,7 @@ public boolean start() throws IOException {
 
     @Override
     public boolean advance() throws IOException {
-      Preconditions.checkState(currentReader != null, "Call start() before advance()");
+      checkState(currentReader != null, "Call start() before advance()");
       if (currentReader.advance()) {
         return true;
       }

sdk/src/main/java/com/google/cloud/dataflow/sdk/io/TextIO.java

@@ -16,6 +16,7 @@
 
 package com.google.cloud.dataflow.sdk.io;
 
+import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkState;
 
 import com.google.cloud.dataflow.sdk.coders.Coder;
@@ -34,9 +35,7 @@
 import com.google.cloud.dataflow.sdk.values.PDone;
 import com.google.cloud.dataflow.sdk.values.PInput;
 import com.google.common.annotations.VisibleForTesting;
-import com.google.common.base.Preconditions;
 import com.google.protobuf.ByteString;
-
 import java.io.IOException;
 import java.io.OutputStream;
 import java.nio.ByteBuffer;
@@ -47,7 +46,6 @@
 import java.nio.charset.StandardCharsets;
 import java.util.NoSuchElementException;
 import java.util.regex.Pattern;
-
 import javax.annotation.Nullable;
 
 /**
@@ -598,7 +596,7 @@ public Bound<T> withSuffix(String nameExtension) {
        * @see ShardNameTemplate
        */
       public Bound<T> withNumShards(int numShards) {
-        Preconditions.checkArgument(numShards >= 0);
+        checkArgument(numShards >= 0);
         return new Bound<>(name, filenamePrefix, filenameSuffix, header, footer, coder, numShards,
             shardTemplate, validate);
       }
@@ -821,7 +819,7 @@ public boolean matches(String filename) {
   private static final Pattern SHARD_OUTPUT_PATTERN = Pattern.compile("@([0-9]+|\\*)");
 
   private static void validateOutputComponent(String partialFilePattern) {
-    Preconditions.checkArgument(
+    checkArgument(
         !SHARD_OUTPUT_PATTERN.matcher(partialFilePattern).find(),
         "Output name components are not allowed to contain @* or @N patterns: "
         + partialFilePattern);