fix: issue 368- consistent namespace scope resolution

[PaurushGarg]

Fixes Issue (368)
In .cc files across whole project, opentelemetry::* is simplified to * , to follow the namespace guidelines. To do this, following
namespace aliases were used, to establish convention:

• namespace common = opentelemetry::common;
• namespace nostd = opentelemetry::nostd;
• namespace trace = opentelemetry::trace;
• namespace trace_api = opentelemetry::trace;
• namespace resource = opentelemetry::sdk::resource;
• namespace exporter_trace = opentelemetry::exporter::trace;
• namespace context = opentelemetry::context;
• namespace metrics_api = opentelemetry::metrics;
• namespace sdkmetrics = opentelemetry::sdk::metrics;
• namespace exportermetrics = opentelemetry::exporter::metrics;
• namespace trace_sdk = opentelemetry::sdk::trace;
• namespace sdktrace = opentelemetry::sdk::trace;
• namespace exporterlogs = opentelemetry::exporter::logs;
• namespace exportertrace = opentelemetry::exporter::trace;
• namespace proto = opentelemetry::proto;
• namespace context = opentelemetry::context;
• namespace otlp = opentelemetry::exporter::otlp;
• namespace plugin = opentelemetry::plugin;
• namespace curl = opentelemetry::ext::http::client::curl;
• namespace http_client = opentelemetry::ext::http::client;
• namespace logs_api = opentelemetry::logs;
• namespace sdklogs = opentelemetry::sdk::logs;

Note: trace and trace_api both are used for opentelemetry::trace;
trace_sdk and sdktrace both are used for opentelemetry::sdk::trace; These were already existing in the code.

Tracking Issue #368

Please provide a brief description of the changes here.
Usage of scope resolution was made consistent across all files using namespace convention and guidelines.

[codecov]

Codecov Report

Merging #1008 (2a1d460) into main (b2a0a56) will not change coverage.
The diff coverage is 90.53%.

@@           Coverage Diff           @@
##             main    #1008   +/-   ##
=======================================
  Coverage   94.41%   94.41%           
=======================================
  Files         158      158           
  Lines        6077     6077           
=======================================
  Hits         5737     5737           
  Misses        340      340           

Impacted Files	Coverage Δ
api/include/opentelemetry/trace/noop.h	86.21% <ø> (ø)
sdk/include/opentelemetry/sdk/trace/sampler.h	100.00% <ø> (ø)
...lude/opentelemetry/sdk/trace/samplers/always_off.h	80.00% <ø> (ø)
...clude/opentelemetry/sdk/trace/samplers/always_on.h	100.00% <ø> (ø)
sdk/src/trace/samplers/parent.cc	100.00% <ø> (ø)
sdk/test/trace/always_on_sampler_test.cc	91.67% <ø> (ø)
api/test/trace/provider_test.cc	80.00% <33.34%> (ø)
...t/src/http/client/curl/http_client_factory_curl.cc	50.00% <50.00%> (ø)
exporters/ostream/src/span_exporter.cc	90.33% <72.73%> (ø)
...lemetry/ext/http/client/curl/http_operation_curl.h	78.09% <73.34%> (ø)
... and 20 more

[lalitb]

Thank you for the PR. I can see it had to go through lots of iteration to make the build work. Changes look good in general, couple of minor comments:

• We can be consistent in namespace alias names:

namespace trace_sdk = opentelemetry::sdk::trace;
namespace sdktrace = opentelemetry::sdk::trace;

If we are using trace_api or trace for api, let's use trace_sdk, metrics_sdk for sdk.

• In header files, there are few namespace aliases that are unknowingly becoming part of public API (namespace pollution). few are here. Do you think it would be easy to remove them ?

labhas@DESKTOP-D0BLHPQ:~/obs/ot/opentelemetry-cpp/api$ find . -name "*.h" | xargs grep 'namespace ' | grep '='
./include/opentelemetry/trace/span_context.h:namespace trace_api = opentelemetry::trace;
labhas@DESKTOP-D0BLHPQ:~/obs/ot/opentelemetry-cpp/api$ cd ../sdk
labhas@DESKTOP-D0BLHPQ:~/obs/ot/opentelemetry-cpp/sdk$ find . -name "*.h" | xargs grep 'namespace ' | grep '='
./src/trace/span.h:namespace trace_api = opentelemetry::trace;
./include/opentelemetry/sdk/metrics/processor.h:namespace sdkmetrics = opentelemetry::sdk::metrics;
./include/opentelemetry/sdk/metrics/controller.h:namespace metrics_api = opentelemetry::metrics;
./include/opentelemetry/sdk/metrics/record.h:namespace metrics_api = opentelemetry::metrics;
./include/opentelemetry/sdk/metrics/aggregator/aggregator.h:namespace metrics_api = opentelemetry::metrics;
./include/opentelemetry/sdk/metrics/aggregator/min_max_sum_count_aggregator.h:namespace metrics_api = opentelemetry::metrics;
./include/opentelemetry/sdk/metrics/aggregator/sketch_aggregator.h:namespace metrics_api = opentelemetry::metrics;
./include/opentelemetry/sdk/metrics/aggregator/gauge_aggregator.h:namespace metrics_api = opentelemetry::metrics;
./include/opentelemetry/sdk/metrics/aggregator/exact_aggregator.h:namespace metrics_api = opentelemetry::metrics;
./include/opentelemetry/sdk/metrics/aggregator/histogram_aggregator.h:namespace metrics_api = opentelemetry::metrics;
./include/opentelemetry/sdk/metrics/aggregator/counter_aggregator.h:namespace metrics_api = opentelemetry::metrics;
./include/opentelemetry/sdk/metrics/sync_instruments.h:namespace metrics_api = opentelemetry::metrics;
./include/opentelemetry/sdk/metrics/meter.h:namespace metrics_api = opentelemetry::metrics;
./include/opentelemetry/sdk/metrics/instrument.h:namespace metrics_api = opentelemetry::metrics;
./include/opentelemetry/sdk/metrics/async_instruments.h:namespace metrics_api = opentelemetry::metrics;
./include/opentelemetry/sdk/trace/samplers/always_off.h:namespace trace_api = opentelemetry::trace;
./include/opentelemetry/sdk/trace/samplers/always_on.h:namespace trace_api = opentelemetry::trace;
./include/opentelemetry/sdk/trace/samplers/trace_id_ratio.h:namespace trace_api = opentelemetry::trace;
./include/opentelemetry/sdk/trace/samplers/parent.h:namespace trace_api = opentelemetry::trace;
./include/opentelemetry/sdk/trace/sampler.h:namespace trace_api = opentelemetry::trace;
labhas@DESKTOP-D0BLHPQ:~/obs/ot/opentelemetry-cpp/sdk$

[lalitb]

@PaurushGarg - Just wondering if you have gone through the earlier comments and any suggestions on it.

[ThomsonTan]

@PaurushGarg let us know if you will get a chance to review all the comments and resolve the conflict, or need our help on it.

[PaurushGarg]

@PaurushGarg - Just wondering if you have gone through the earlier comments and any suggestions on it.

@lalitb Sorry it took some time. I have updated both the comments regarding trace_sdk and metric_sdk, and also updated the header files to remove the namespace aliases.

[PaurushGarg]

@PaurushGarg let us know if you will get a chance to review all the comments and resolve the conflict, or need our help on it.

@ThomsonTan Sorry it took some time. I have updated both the comments regarding trace_sdk and metric_sdk, and also updated the header files to removes the namespace aliases.

[ThomsonTan]

@lalitb do you have any other comments?

[lalitb]

@lalitb do you have any other comments?

No, it looks good now. Thanks, @PaurushGarg for your efforts.