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From GitBox <...@apache.org>
Subject [GitHub] [drill] arina-ielchiieva commented on a change in pull request #1683: DRILL-6952: Host compliant text reader on the row set framework
Date Sun, 10 Mar 2019 16:03:49 GMT
arina-ielchiieva commented on a change in pull request #1683: DRILL-6952: Host compliant text
reader on the row set framework
URL: https://github.com/apache/drill/pull/1683#discussion_r264045583
 
 

 ##########
 File path: exec/java-exec/src/main/java/org/apache/drill/exec/store/easy/text/compliant/v3/TextInput.java
 ##########
 @@ -0,0 +1,356 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.drill.exec.store.easy.text.compliant.v3;
+
+import io.netty.buffer.DrillBuf;
+import io.netty.util.internal.PlatformDependent;
+
+import java.io.EOFException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.ByteBuffer;
+
+import org.apache.hadoop.fs.ByteBufferReadable;
+import org.apache.hadoop.fs.FSDataInputStream;
+import org.apache.hadoop.fs.Seekable;
+import org.apache.hadoop.io.compress.CompressionInputStream;
+
+import org.apache.drill.shaded.guava.com.google.common.base.Preconditions;
+
+import static org.apache.drill.exec.memory.BoundsChecking.rangeCheck;
+
+/**
+ * Class that fronts an InputStream to provide a byte consumption interface.
+ * Also manages only reading lines to and from each split.
+ */
+final class TextInput {
+
+  private final byte[] lineSeparator;
+  private final byte normalizedLineSeparator;
+  private final TextParsingSettingsV3 settings;
+
+  private long lineCount;
+  private long charCount;
+
+  /**
+   * The starting position in the file.
+   */
+  private final long startPos;
+  private final long endPos;
+
+  private long streamPos;
+
+  private final Seekable seekable;
+  private final FSDataInputStream inputFS;
+  private final InputStream input;
+
+  private final DrillBuf buffer;
+  private final ByteBuffer underlyingBuffer;
+  private final long bStart;
+  private final long bStartMinus1;
+
+  private final boolean bufferReadable;
+
+  /**
+   * Whether there was a possible partial line separator on the previous
+   * read so we dropped it and it should be appended to next read.
+   */
+  private int remByte = -1;
+
+  /**
+   * The current position in the buffer.
+   */
+  public int bufferPtr;
+
+  /**
+   * The quantity of valid data in the buffer.
+   */
+  public int length = -1;
+
+  private boolean endFound = false;
+
+  /**
+   * Creates a new instance with the mandatory characters for handling newlines transparently.
+   * lineSeparator the sequence of characters that represent a newline, as defined in {@link
Format#getLineSeparator()}
+   * normalizedLineSeparator the normalized newline character (as defined in {@link Format#getNormalizedNewline()})
that is used to replace any lineSeparator sequence found in the input.
+   */
+  public TextInput(TextParsingSettingsV3 settings, InputStream input, DrillBuf readBuffer,
long startPos, long endPos) {
+    this.lineSeparator = settings.getNewLineDelimiter();
+    byte normalizedLineSeparator = settings.getNormalizedNewLine();
+    Preconditions.checkArgument(input instanceof Seekable, "Text input only supports an InputStream
that supports Seekable.");
+    boolean isCompressed = input instanceof CompressionInputStream;
+    Preconditions.checkArgument(!isCompressed || startPos == 0, "Cannot use split on compressed
stream.");
+
+    // splits aren't allowed with compressed data.  The split length will be the compressed
size which means we'll normally end prematurely.
+    if(isCompressed && endPos > 0){
+      endPos = Long.MAX_VALUE;
+    }
+
+    this.input = input;
+    this.seekable = (Seekable) input;
+    this.settings = settings;
+
+    if(input instanceof FSDataInputStream){
+      this.inputFS = (FSDataInputStream) input;
+      this.bufferReadable = inputFS.getWrappedStream() instanceof ByteBufferReadable;
+    }else{
+      this.inputFS = null;
+      this.bufferReadable = false;
+    }
+
+    this.startPos = startPos;
+    this.endPos = endPos;
+
+    this.normalizedLineSeparator = normalizedLineSeparator;
+
+    this.buffer = readBuffer;
+    this.bStart = buffer.memoryAddress();
+    this.bStartMinus1 = bStart -1;
+    this.underlyingBuffer = buffer.nioBuffer(0, buffer.capacity());
+  }
+
+  /**
+   * Test the input to position for read start.  If the input is a non-zero split or
+   * splitFirstLine is enabled, input will move to appropriate complete line.
+   * @throws IOException
+   */
+  final void start() throws IOException {
+    lineCount = 0;
+    if(startPos > 0){
+      seekable.seek(startPos);
+    }
+
+    updateBuffer();
+    if (length > 0) {
+      if (startPos > 0 || settings.isSkipFirstLine()) {
+
+        // move to next full record.
+        skipLines(1);
+      }
+    }
+  }
+
+
+  /**
+   * Helper method to get the most recent characters consumed since the last record started.
+   * May get an incomplete string since we don't support stream rewind.  Returns empty string
for now.
+   * @return String of last few bytes.
+   * @throws IOException
+   */
+  public String getStringSinceMarkForError() throws IOException {
+    return " ";
+  }
+
+  long getPos() {
+    return streamPos + bufferPtr;
+  }
+
+  public void mark() { }
+
+  /**
+   * read some more bytes from the stream.  Uses the zero copy interface if available.  Otherwise,
does byte copy.
+   * @throws IOException
+   */
+  private void read() throws IOException {
+    if(bufferReadable){
+
+      if (remByte != -1) {
+        for (int i = 0; i <= remByte; i++) {
+          underlyingBuffer.put(lineSeparator[i]);
+        }
+        remByte = -1;
+      }
+      length = inputFS.read(underlyingBuffer);
+
+    } else {
+      byte[] b = new byte[underlyingBuffer.capacity()];
+      if (remByte != -1){
+        int remBytesNum = remByte + 1;
+        System.arraycopy(lineSeparator, 0, b, 0, remBytesNum);
+        length = input.read(b, remBytesNum, b.length - remBytesNum);
+        remByte = -1;
+      } else {
+        length = input.read(b);
+      }
+      underlyingBuffer.put(b);
+    }
+  }
+
+
+  /**
+   * Read more data into the buffer.  Will also manage split end conditions.
+   * @throws IOException
+   */
+  private void updateBuffer() throws IOException {
+    streamPos = seekable.getPos();
+    underlyingBuffer.clear();
+
+    if (endFound) {
+      length = -1;
+      return;
+    }
+
+    read();
+
+    // check our data read allowance.
+    if (streamPos + length >= this.endPos) {
+      updateLengthBasedOnConstraint();
+    }
+
+    charCount += bufferPtr;
+    bufferPtr = 1;
+
+    buffer.writerIndex(underlyingBuffer.limit());
+    buffer.readerIndex(underlyingBuffer.position());
+  }
+
+  /**
+   * Checks to see if we can go over the end of our bytes constraint on the data.  If so,
+   * adjusts so that we can only read to the last character of the first line that crosses
+   * the split boundary.
+   */
+  private void updateLengthBasedOnConstraint() {
+    final long max = bStart + length;
+    for (long m = bStart + (endPos - streamPos); m < max; m++) {
+      for (int i = 0; i < lineSeparator.length; i++) {
+        long mPlus = m + i;
+        if (mPlus < max) {
+          // we found a line separator and don't need to consult the next byte.
+          if (lineSeparator[i] == PlatformDependent.getByte(mPlus) && i == lineSeparator.length
- 1) {
+            length = (int) (mPlus - bStart) + 1;
+            endFound = true;
+            return;
+          }
+        } else {
+          // the last N characters of the read were remnant bytes. We'll hold off on dealing
with these bytes until the next read.
+          remByte = i;
+          length = length - i;
+          return;
+        }
+      }
+    }
+  }
+
+  /**
+   * Get next byte from stream.  Also maintains the current line count.  Will throw a StreamFinishedPseudoException
+   * when the stream has run out of bytes.
+   * @return next byte from stream.
+   * @throws IOException
+   */
+  public final byte nextChar() throws IOException {
+    byte byteChar = nextCharNoNewLineCheck();
+    int bufferPtrTemp = bufferPtr - 1;
+    if (byteChar == lineSeparator[0]) {
+      for (int i = 1; i < lineSeparator.length; i++, bufferPtrTemp++) {
+        if (lineSeparator[i] != buffer.getByte(bufferPtrTemp)) {
+          return byteChar;
+        }
+      }
+
+      lineCount++;
+      byteChar = normalizedLineSeparator;
+
+      // we don't need to update buffer position if line separator is one byte long
+      if (lineSeparator.length > 1) {
+        bufferPtr += (lineSeparator.length - 1);
+        if (bufferPtr >= length) {
+          if (length != -1) {
+            updateBuffer();
+          } else {
+            throw StreamFinishedPseudoException.INSTANCE;
+          }
+        }
+      }
+    }
+
+    return byteChar;
+  }
+
+  /**
+   * Get next byte from stream.  Do no maintain any line count  Will throw a StreamFinishedPseudoException
+   * when the stream has run out of bytes.
+   * @return next byte from stream.
+   * @throws IOException
+   */
+  public final byte nextCharNoNewLineCheck() throws IOException {
+
+    if (length == -1) {
+      throw StreamFinishedPseudoException.INSTANCE;
+    }
+
+    rangeCheck(buffer, bufferPtr - 1, bufferPtr);
+
+    byte byteChar = PlatformDependent.getByte(bStartMinus1 + bufferPtr);
+
+    if (bufferPtr >= length) {
+      if (length != -1) {
+        updateBuffer();
+        bufferPtr--;
+      } else {
+        throw StreamFinishedPseudoException.INSTANCE;
+      }
+    }
+
+    bufferPtr++;
+    return byteChar;
+  }
+
+  /**
+   * Number of lines read since the start of this split.
+   * @return
+   */
+  public final long lineCount() {
+    return lineCount;
+  }
+
+  /**
+   * Skip forward the number of line delimiters.  If you are in the middle of a line,
+   * a value of 1 will skip to the start of the next record.
+   * @param lines Number of lines to skip.
+   * @throws IOException
+   */
+  public final void skipLines(int lines) throws IOException {
+    if (lines < 1) {
+      return;
+    }
+    long expectedLineCount = this.lineCount + lines;
+
+    try {
+      do {
+        nextChar();
+      } while (lineCount < expectedLineCount);
+      if (lineCount < lines) {
+        throw new IllegalArgumentException("Unable to skip " + lines + " lines from line
" + (expectedLineCount - lines) + ". End of input reached");
+      }
+    } catch (EOFException ex) {
 
 Review comment:
   Please include exception `ex` as well.

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