Simplify LogExporter::Export interface

[lalitb]

Changes

1. The Exporter::export interface is modified to accept the vector of pair/tuple of reference to LogRecord and InstrumentationLib, instead of Cow of LogData.

Before:

async fn export<'a>(&mut self, batch: Vec<Cow<'a, LogData>>) -> LogResult<()>;

After:

async fn export( &mut self, batch: Vec<(&LogRecord, &InstrumentationLibrary)>) -> LogResult<()>;

This simplifies the processing for exporters, as they don't need to check whether the object is borrowed, or owned. Exporter needs to ensure to create the copy of LogRecord and/or InstrumentationLib whenever needed.

2. The LogData structure is not part of the export interface. So it has been moved from opentelemetry_sdk::export::logs to opentelemetry_sdk::logs:: namespace.

Merge requirement checklist

• CONTRIBUTING guidelines followed
• Unit tests added/updated (if applicable)
• Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

Attention: Patch coverage is 54.21687% with 38 lines in your changes missing coverage. Please review.

Project coverage is 77.1%. Comparing base (056d2ae) to head (8c22d38).
Report is 1 commits behind head on main.

Files	Patch %	Lines
opentelemetry-stdout/src/logs/transform.rs	0.0%	21 Missing ⚠️
opentelemetry-proto/src/transform/logs.rs	78.3%	8 Missing ⚠️
opentelemetry-otlp/src/exporter/http/logs.rs	0.0%	2 Missing ⚠️
opentelemetry-otlp/src/exporter/tonic/logs.rs	0.0%	2 Missing ⚠️
opentelemetry-stdout/src/logs/exporter.rs	0.0%	2 Missing ⚠️
opentelemetry-otlp/src/exporter/http/mod.rs	0.0%	1 Missing ⚠️
opentelemetry-otlp/src/logs.rs	0.0%	1 Missing ⚠️
opentelemetry-sdk/src/logs/log_processor.rs	90.0%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #2041     +/-   ##
=======================================
+ Coverage   77.0%   77.1%   +0.1%     
=======================================
  Files        123     123             
  Lines      21111   21104      -7     
=======================================
+ Hits       16260   16276     +16     
+ Misses      4851    4828     -23     

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[cijothomas]

BatchProcessor is now doing an extra cloning - 1st one occurs when it receives the &mut LogData, so it can save it to channel. And its drained to a Vec! later, which was passed as-is to Exporter previously. Now another Vec! needs to be created to pass on to exporter.
Something we can revisit and address in the future.

[lalitb]

This operation is only creating references and collecting them, no cloning of data is happening.

[cijothomas]

Isn't the collect making a new Vec! ?

[lalitb]

Oh yes, I was talking specifically about cloning. Need to revisit vector later.