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https://github.com/open-telemetry/opentelemetry-go.git
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91091b44eb
* Add comments on needed filed alignment Add comment about alignment requirements to all struct fields who's values are passed to 64-bit atomic operations. Update any struct's field ordering if one or more of those fields has alignment requirements to support 64-bit atomic operations. * Add 64-bit alignment tests Most `struct` that have field alignment requirements are now statically validated prior to testing. The only `struct`s not validated that have these requirements are ones defined in tests themselves where multiple `TestMain` functions would be needed to test them. Given the fields are already identified with comments specifying the alignment requirements and they are in the test themselves, this seems like an OK omission. Co-authored-by: Liz Fong-Jones <elizabeth@ctyalcove.org>
73 lines
2.3 KiB
Go
73 lines
2.3 KiB
Go
// Copyright 2019, OpenTelemetry Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package counter // import "go.opentelemetry.io/otel/sdk/metric/aggregator/counter"
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import (
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"context"
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"go.opentelemetry.io/otel/api/core"
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export "go.opentelemetry.io/otel/sdk/export/metric"
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"go.opentelemetry.io/otel/sdk/export/metric/aggregator"
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)
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// Aggregator aggregates counter events.
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type Aggregator struct {
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// current holds current increments to this counter record
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// current needs to be aligned for 64-bit atomic operations.
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current core.Number
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// checkpoint is a temporary used during Checkpoint()
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// checkpoint needs to be aligned for 64-bit atomic operations.
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checkpoint core.Number
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}
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var _ export.Aggregator = &Aggregator{}
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var _ aggregator.Sum = &Aggregator{}
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// New returns a new counter aggregator implemented by atomic
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// operations. This aggregator implements the aggregator.Sum
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// export interface.
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func New() *Aggregator {
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return &Aggregator{}
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}
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// Sum returns the last-checkpointed sum. This will never return an
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// error.
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func (c *Aggregator) Sum() (core.Number, error) {
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return c.checkpoint, nil
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}
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// Checkpoint atomically saves the current value and resets the
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// current sum to zero.
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func (c *Aggregator) Checkpoint(ctx context.Context, _ *export.Descriptor) {
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c.checkpoint = c.current.SwapNumberAtomic(core.Number(0))
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}
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// Update atomically adds to the current value.
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func (c *Aggregator) Update(_ context.Context, number core.Number, desc *export.Descriptor) error {
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c.current.AddNumberAtomic(desc.NumberKind(), number)
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return nil
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}
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// Merge combines two counters by adding their sums.
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func (c *Aggregator) Merge(oa export.Aggregator, desc *export.Descriptor) error {
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o, _ := oa.(*Aggregator)
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if o == nil {
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return aggregator.NewInconsistentMergeError(c, oa)
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}
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c.checkpoint.AddNumber(desc.NumberKind(), o.checkpoint)
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return nil
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}
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