[fallintoplace]

What

Avoid allocating a String for each 64-bit JSON integer.

Why

The values must be quoted, but to_string creates a temporary String.

Implementation

• Format each value with itoa in a stack buffer.
• Pass the formatted value to the serializer.

Benchmark

Rust 1.95, Ubuntu runner, release build, 11 interleaved samples.

• int64, 32 values: 742.6 to 407.5 ns/op (1.82x faster).
• uint64, 32 values: 747.5 to 463.6 ns/op (1.61x faster).
• int64, 4,096 values: 94.47 to 57.42 us/op (1.65x faster).
• uint64, 4,096 values: 96.42 to 60.91 us/op (1.58x faster).
• Benchmark run.

[github-actions]

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