Optimize memory allocation with buffer pools and slice reuse

[Copilot]

Addresses potential memory issues by reducing allocations in hot paths through buffer pooling and capacity-aware buffer management.

Changes

Buffer Pool Infrastructure (pkg/utils/buffer.go)

• Added BufferPool type wrapping sync.Pool with configurable sizes
• Global pools: SmallBufferPool (1KB), MediumBufferPool (32KB), LargeBufferPool (64KB)
• BytesBufferPool for bytes.Buffer reuse with GetBytesBuffer()/PutBytesBuffer() helpers

FTP File Operations (pkg/proxy/recorder.go)

• Pool-based 32KB buffer reuse in FTPFileInfo.WriteFromReader() instead of per-call allocation

Zmodem Parsing (pkg/zmodem/zsession.go)

• Reuse parsedSubPacket slice capacity via s.parsedSubPacket = s.parsedSubPacket[:0]
• Reset subPacketBuf when capacity exceeds 64KB to prevent memory bloat

Terminal Parser (pkg/proxy/parsercmd.go)

• Added resetInputBuf() to reset buffers and reclaim memory when capacity exceeds threshold

Example

// Before: allocates 32KB per call
buf := make([]byte, 32*1024)

// After: reuses pooled buffer
bufPtr := ftpReadBufferPool.Get().(*[]byte)
buf := *bufPtr
defer ftpReadBufferPool.Put(bufPtr)

Benchmarks

BenchmarkBytesBufferPoolGet    0 B/op   0 allocs/op
BenchmarkRawBytesBufferAlloc  64 B/op   1 allocs/op

Original prompt

分析可能存在的内存问题，优化内存分配

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[sonarqubecloud]

Quality Gate passed

Issues
12 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud