Vanillaxi opened a new pull request, #3403:
URL: https://github.com/apache/dubbo-go/pull/3403
## What is changed
This PR optimizes `common.URL.CloneWithFilter()` and `common.URL.MergeURL()`
to reduce unnecessary params copying and repeated locking on clone/merge paths.
Changes are limited to:
- `common/url.go`
- `common/url_test.go`
Main changes:
1. Add internal helper `copyURLValues`
- Deep-copies `url.Values`
- Preserves multi-value params
- Keeps `nil` input as `nil`
- Reuses the helper in `CopyParams()` without changing its public behavior
2. Add internal helper `valuesHasNonDefaultParam`
- Preserves the existing `GetNonDefaultParam()` semantics
- Treats missing keys or `values.Get(key) == ""` as not found
- Avoids replacing this behavior with a simple map key-existence check
3. Optimize `CloneWithFilter()`
- Avoids `RangeParams()` + calling `SetParam()` for each param
- Copies filtered params directly under a single read lock
- Deep-copies `[]string` values to preserve multi-value params
- Preallocates the params map for larger param sets to reduce map growth
- Avoids aggressive preallocation for small param sets
4. Optimize `MergeURL()`
- Keeps `mergedURL := c.Clone()` to preserve existing clone behavior
- Reuses the cloned local `mergedURL.params` directly
- Avoids the extra `mergedURL.GetParams()` deep copy
- Reads `anotherUrl.params` under a single read lock
- Deep-copies remote `[]string` values when merging
- Preserves existing timestamp, method params, attributes, `Methods`, and
`SubURL` behavior
5. Add tests
- `TestCloneWithFilterPreservesMultiValueParams`
- `TestMergeURLPreservesMultiValueParams`
- `TestMergeURLUsesNonDefaultParamSemantics`
## Why
`CloneWithFilter()` and `MergeURL()` are used in registry, directory,
configurator, and invoker update flows.
The previous implementation performed extra params map copies and repeated
locking through public helper methods. This PR keeps public `GetParams()` /
`CopyParams()` semantics unchanged while reducing internal copy/lock overhead.
## Benchmark
Benchmarks were measured on the same machine with Go 1.25.
Environment:
```text
goos: darwin
goarch: arm64
cpu: Apple M5
pkg: dubbo.apache.org/dubbo-go/v3/common
```
Command:
```bash
go test ./common -bench 'BenchmarkURL(CloneWithFilter|MergeURL)' -benchmem
-run '^$' -count=5
```
Summary of key results:
| Benchmark | before ns/op | after
ns/op | before B/op | after B/op | before allocs/op | after allocs/op |
| ------------------------------------------------ | ------------ |
----------- | ----------- | ---------- | ---------------- | --------------- |
| `CloneWithFilter/params_32` | 3309 | 2082
| 6232 | 3752 | 49 | 45 |
| `CloneWithFilter/params_256` | 32489 | 11701
| 47928 | 26408 | 279 | 269 |
| `CloneWithFilter/params_1024` | 122685 | 49558
| 207785 | 115280 | 1054 | 1039 |
| `CloneWithFilter/params_1024_exclude_20_percent` | 101994 | 62952
| 106120 | 62808 | 844 | 832 |
| `CloneWithFilter/params_1024_reserve_20_percent` | 378304 | 235029
| 25240 | 14632 | 221 | 213 |
| `MergeURL/params_1_with_method_params` | 6196 | 3916
| 6360 | 4016 | 103 | 69 |
| `MergeURL/params_32_with_method_params` | 13318 | 6487
| 19888 | 10416 | 218 | 116 |
| `MergeURL/params_256_with_method_params` | 65596 | 23168
| 103280 | 29456 | 1006 | 450 |
| `MergeURL/params_1024_with_method_params` | 284256 | 96447
| 447026 | 124472 | 3705 | 1604 |
Notable improvements:
```text
BenchmarkURLMergeURL/params_1024_with_method_params
ns/op: 284256 -> 96447 (~66.1% reduction)
B/op: 447026 -> 124472 (~72.2% reduction)
allocs/op: 3705 -> 1604 (~56.7% reduction)
BenchmarkURLCloneWithFilter/params_1024
ns/op: 122685 -> 49558 (~59.6% reduction)
B/op: 207785 -> 115280 (~44.5% reduction)
allocs/op: 1054 -> 1039 (~1.4% reduction)
```
## Test
```bash
go test ./common
```
Passed.
## Related issue
Fixes #3392
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