### What changes were proposed in this pull request?
1. Remove duplicated code in the form of `readXXX` in `VectorizedRleValuesReader`. For instance:
```java
public void readIntegers(
int total,
WritableColumnVector c,
int rowId,
int level,
VectorizedValuesReader data) throws IOException {
int left = total;
while (left > 0) {
if (this.currentCount == 0) this.readNextGroup();
int n = Math.min(left, this.currentCount);
switch (mode) {
case RLE:
if (currentValue == level) {
data.readIntegers(n, c, rowId);
} else {
c.putNulls(rowId, n);
}
break;
case PACKED:
for (int i = 0; i < n; ++i) {
if (currentBuffer[currentBufferIdx++] == level) {
c.putInt(rowId + i, data.readInteger());
} else {
c.putNull(rowId + i);
}
}
break;
}
rowId += n;
left -= n;
currentCount -= n;
}
}
```
and replace with:
```java
public void readBatch(
int total,
int offset,
WritableColumnVector values,
int maxDefinitionLevel,
VectorizedValuesReader valueReader,
ParquetVectorUpdater updater) throws IOException {
int left = total;
while (left > 0) {
if (this.currentCount == 0) this.readNextGroup();
int n = Math.min(left, this.currentCount);
switch (mode) {
case RLE:
if (currentValue == maxDefinitionLevel) {
updater.updateBatch(n, offset, values, valueReader);
} else {
values.putNulls(offset, n);
}
break;
case PACKED:
for (int i = 0; i < n; ++i) {
if (currentBuffer[currentBufferIdx++] == maxDefinitionLevel) {
updater.update(offset + i, values, valueReader);
} else {
values.putNull(offset + i);
}
}
break;
}
offset += n;
left -= n;
currentCount -= n;
}
}
```
where the `ParquetVectorUpdater` is type specific, and has different implementations under `updateBatch` and `update`. Together, this also changes code paths handling timestamp types to use the batch read API for decoding definition levels.
2. Similar to the above, this removes code duplication in `VectorizedColumnReader.decodeDictionaryIds`. Now different implementations are under `ParquetVectorUpdater.decodeSingleDictionaryId`.
### Why are the changes needed?
`VectorizedRleValuesReader` and `VectorizedColumnReader` are becoming increasingly harder to maintain, as any change touches the above logic **will need to be replicated in 20+ places**. The issue becomes even more serious when we are going to implement column index (for instance, see how the change [here](https://github.com/apache/spark/pull/32753/files#diff-a01e174e178366aadf07f64ee690d47d343b2ca416a4a2b2ea735887c22d5934R191) has to be replicated multiple times) and complex type support (in progress) for the vectorized path.
In addition, currently dictionary decoding (see `VectorizedColumnReader.decodeDictionaryIds`) and non-dictionary decoding are handled separately, and therefore the same (very complicated) branching logic based on input Spark & Parquet types have to be replicated in two places, which is another burden for code maintenance.
The original intention is for performance. However these days JIT compilers tend to be very effective on this and will inline virtual calls aggressively to eliminate the method invocation costs (see [this](https://shipilev.net/blog/2015/black-magic-method-dispatch/) and [this](http://insightfullogic.com/blog/2014/may/12/fast-and-megamorphic-what-influences-method-invoca/)). I've also done benchmarks using a modified `DataSourceReadBenchmark` and `DateTimeRebaseBenchmark` and the result is almost exact the same before and after the change. The results can be found [here](https://gist.github.com/sunchao/674afbf942ccc2370bdcfa33efb4471c), and [here's](https://github.com/sunchao/spark/tree/parquet-refactor) the source code.
### Does this PR introduce _any_ user-facing change?
No
### How was this patch tested?
Existing tests.
Closes#32777 from sunchao/SPARK-35640.
Authored-by: Chao Sun <sunchao@apple.com>
Signed-off-by: DB Tsai <d_tsai@apple.com>
e9ccf4a50c