perf(java): Reduce performance regression caused by deleteCharAt #1591
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Signed-off-by: LiangliangSui <coolsui.coding@gmail.com>
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MetaString is not int critical path, maybe we don't need to optimize this? |
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Through this optimization we can also reduce the operations of appending and deleting to StringBuilder. Although it is not on the critical path, it is still profitable. |
| @@ -74,7 +74,7 @@ private String decodeLowerSpecial(byte[] data) { | |||
| boolean stripLastChar = (data[0] & 0x80) != 0; // Check the first bit of the first byte | |||
| int bitMask = 0b11111; // 5 bits for the mask | |||
| int bitIndex = 1; // Start from the second bit | |||
| while (bitIndex + 5 <= totalBits) { | |||
| while (bitIndex + 5 <= totalBits && !(stripLastChar && (bitIndex + 2 * 5 > totalBits))) { | |||
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Could you explain what !(stripLastChar && (bitIndex + 2 * 5 > totalBits)) mean? It seems not intutive to me.
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(bitIndex + 2 * 5 > totalBits) indicates that the current character is the last character.
!(stripLastChar && (bitIndex + 2 * 5 > totalBits)) means that if the current character is the last character and the last character needs to be deleted, the while loop will not be entered.
This can reduce the last redundant StringBuilder#append -> StringBuilder#deleteCharAt
What does this PR do?
This PR reduces the performance regression caused by StringBuilder#deleteCharAt, avoids using deleteCharAt, and makes early judgments in while.
Related issues
Does this PR introduce any user-facing change?
Benchmark
before this PR
with this pr
