jt2594838 commented on a change in pull request #1727:
URL: https://github.com/apache/incubator-iotdb/pull/1727#discussion_r487717421
##########
File path:
server/src/main/java/org/apache/iotdb/db/writelog/io/SingleFileLogReader.java
##########
@@ -53,54 +54,69 @@
private boolean fileCorrupted = false;
+ private boolean hasNext = false;
+
public SingleFileLogReader(File logFile) throws FileNotFoundException {
open(logFile);
}
@Override
public boolean hasNext() {
- try {
- if (batchLogReader != null && batchLogReader.hasNext()) {
- return true;
- }
-
- if (logStream.available() < LEAST_LOG_SIZE) {
- return false;
- }
- int logSize = logStream.readInt();
- if (logSize <= 0) {
- return false;
- }
- buffer = new byte[logSize];
+ if (Objects.nonNull(batchLogReader)) {
+ hasNext = batchLogReader.hasNext();
- int readLen = logStream.read(buffer, 0, logSize);
- if (readLen < logSize) {
- throw new IOException("Reach eof");
+ if (hasNext) {
+ return hasNext;
}
+ }
- final long checkSum = logStream.readLong();
- checkSummer.reset();
- checkSummer.update(buffer, 0, logSize);
- if (checkSummer.getValue() != checkSum) {
- throw new IOException(String.format("The check sum of the No.%d log
batch is incorrect! In "
- + "file: "
- + "%d Calculated: %d.", idx, checkSum, checkSummer.getValue()));
+ try {
+ while (logStream.available() > LEAST_LOG_SIZE) {
+ int logSize = logStream.readInt();
+ if (logSize <= 0) {
+ hasNext = false;
+ return hasNext;
+ }
+
+ byte[] buffer = new byte[logSize];
+ int readLen = logStream.read(buffer, 0, logSize);
+ if (readLen < logSize) {
+ throw new IOException("Reach eof");
+ }
+
+ final long checkSum = logStream.readLong();
+ checkSummer.reset();
+ checkSummer.update(buffer, 0, logSize);
+ if (checkSummer.getValue() != checkSum) {
+ throw new IOException(String.format("The check sum of the No.%d log
batch is incorrect! In "
+ + "file: "
+ + "%d Calculated: %d.", idx, checkSum,
checkSummer.getValue()));
+ }
+
+ batchLogReader = new BatchLogReader(ByteBuffer.wrap(buffer));
+ if (batchLogReader.isFileCorrupted()) {
+ fileCorrupted = true;
+ hasNext = false;
+ return hasNext;
+ }
+
+ if (batchLogReader.hasNext()) {
+ hasNext = true;
+ return hasNext;
+ }
}
-
- batchLogReader = new BatchLogReader(ByteBuffer.wrap(buffer));
- fileCorrupted = fileCorrupted || batchLogReader.isFileCorrupted();
} catch (Exception e) {
logger.error("Cannot read more PhysicalPlans from {} because", filepath,
e);
- fileCorrupted = true;
- return false;
}
- return true;
+
+ hasNext = false;
+ return hasNext;
}
@Override
public PhysicalPlan next() {
- if (!hasNext()){
+ if (!hasNext){
Review comment:
`next()` in an iterator should not depend on `hasNext()`, that is, the
caller should be able to iterate without calling `hasNext()`. While in your
implementation, if the caller calls `next()` without calling `hasNext()`, it
will get nothing at all.
And I do not understand other code changes in this PR, could you please
explain their improvements to me?
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