[SDK] Replace SpinLockMutex with std::mutex in the metrics library

CHANGELOG.md

@@ -56,6 +56,9 @@ Increment the:
   (programmatic and from yaml)
   ([#4366](https://github.com/open-telemetry/opentelemetry-cpp/pull/4366))
 
+* [SDK] Replace SpinLockMutex with std::mutex in the metrics storage clases
+  [#4416](https://github.com/open-telemetry/opentelemetry-cpp/pull/4416)
+
 * [CONFIGURATION/BUILD] Add resource detector targets and README
   [#4430](https://github.com/open-telemetry/opentelemetry-cpp/pull/4430)
 

sdk/include/opentelemetry/sdk/metrics/state/async_metric_storage.h

@@ -63,7 +63,7 @@ class AsyncMetricStorage : public MetricStorage, public AsyncWritableMetricStora
     // Async counter always record monotonically increasing values, and the
     // exporter/reader can request either for delta or cumulative value.
     // So we convert the async counter value to delta before passing it to temporal storage.
-    std::lock_guard<opentelemetry::common::SpinLockMutex> guard(hashmap_lock_);
+    std::lock_guard<std::mutex> guard(hashmap_lock_);
 #ifdef ENABLE_METRICS_EXEMPLAR_PREVIEW
     const bool offer_exemplars =
         ExemplarFilterEnabled(exemplar_filter_type_, opentelemetry::context::Context{});
@@ -130,7 +130,7 @@ class AsyncMetricStorage : public MetricStorage, public AsyncWritableMetricStora
 
     std::shared_ptr<AttributesHashMap> delta_metrics = nullptr;
     {
-      std::lock_guard<opentelemetry::common::SpinLockMutex> guard(hashmap_lock_);
+      std::lock_guard<std::mutex> guard(hashmap_lock_);
       delta_metrics = std::move(delta_hash_map_);
       delta_hash_map_ =
           std::make_unique<AttributesHashMap>(aggregation_config_->cardinality_limit_);
@@ -148,7 +148,7 @@ class AsyncMetricStorage : public MetricStorage, public AsyncWritableMetricStora
   const AggregationConfig *aggregation_config_;
   std::unique_ptr<AttributesHashMap> cumulative_hash_map_;
   std::unique_ptr<AttributesHashMap> delta_hash_map_;
-  opentelemetry::common::SpinLockMutex hashmap_lock_;
+  std::mutex hashmap_lock_;
 #ifdef ENABLE_METRICS_EXEMPLAR_PREVIEW
   ExemplarFilterType exemplar_filter_type_;
   nostd::shared_ptr<ExemplarReservoir> exemplar_reservoir_;

sdk/include/opentelemetry/sdk/metrics/state/sync_metric_storage.h

@@ -11,7 +11,6 @@
 #include <unordered_map>
 
 #include "opentelemetry/common/key_value_iterable.h"
-#include "opentelemetry/common/spin_lock_mutex.h"
 #include "opentelemetry/common/timestamp.h"
 #include "opentelemetry/context/context.h"
 #include "opentelemetry/nostd/function_ref.h"
@@ -197,7 +196,7 @@ class SyncMetricStorage : public MetricStorage, public SyncWritableMetricStorage
   std::shared_ptr<BoundSyncWritableMetricStorage> Bind(
       const opentelemetry::common::KeyValueIterable &attributes) noexcept override;
 
-  // Internal: stable bound entry. Self-contained: owns its own spinlock and
+  // Internal: stable bound entry. Self-contained: owns its own mutex and
   // aggregation so the user-held handle stays safe to call even if the parent
   // SyncMetricStorage is destroyed first (writes simply have no observer).
   // Collect() rotates current_ when dirty so bound + unbound writes for the
@@ -226,7 +225,7 @@ class SyncMetricStorage : public MetricStorage, public SyncWritableMetricStorage
     InstrumentValueType value_type_;
     MetricAttributes attributes_;
     // Protected by lock_.
-    opentelemetry::common::SpinLockMutex lock_;
+    std::mutex lock_;
     std::unique_ptr<Aggregation> current_;
     bool dirty_ = false;
   };

sdk/include/opentelemetry/sdk/metrics/state/temporal_metric_storage.h

@@ -5,9 +5,9 @@
 
 #include <list>
 #include <memory>
+#include <mutex>
 #include <unordered_map>
 
-#include "opentelemetry/common/spin_lock_mutex.h"
 #include "opentelemetry/common/timestamp.h"
 #include "opentelemetry/nostd/function_ref.h"
 #include "opentelemetry/nostd/span.h"
@@ -54,7 +54,7 @@ class TemporalMetricStorage
   std::unordered_map<CollectorHandle *, LastReportedMetrics> last_reported_metrics_;
 
   // Lock while building metrics
-  mutable opentelemetry::common::SpinLockMutex lock_;
+  mutable std::mutex lock_;
   const AggregationConfig *aggregation_config_;
   opentelemetry::common::SystemTimestamp last_delta_collection_ts_;
   bool has_last_delta_collection_ts_ = false;

sdk/src/metrics/state/sync_metric_storage.cc

@@ -22,7 +22,6 @@
 #  include <unordered_set>
 #  include <vector>
 
-#  include "opentelemetry/common/spin_lock_mutex.h"
 #  include "opentelemetry/sdk/common/global_log_handler.h"
 #  include "opentelemetry/sdk/metrics/aggregation/aggregation.h"
 #  include "opentelemetry/sdk/metrics/data/exemplar_data.h"
@@ -47,7 +46,7 @@ bool SyncMetricStorage::Collect(CollectorHandle *collector,
   std::shared_ptr<AttributesHashMap> delta_metrics = nullptr;
 #ifdef OPENTELEMETRY_HAVE_METRICS_BOUND_INSTRUMENTS_PREVIEW
   // Snapshot of bound entries (under map lock) that we will rotate without
-  // holding the map lock. Each entry has its own spinlock for the swap.
+  // holding the map lock. Each entry has its own mutex for the swap.
   std::vector<std::shared_ptr<BoundEntry>> entry_snapshot;
 #endif
   {
@@ -66,7 +65,7 @@ bool SyncMetricStorage::Collect(CollectorHandle *collector,
       bool can_erase = false;
       if (it->second.use_count() == 1)
       {
-        std::lock_guard<opentelemetry::common::SpinLockMutex> g(it->second->lock_);
+        std::lock_guard<std::mutex> g(it->second->lock_);
         can_erase = !it->second->dirty_;
       }
       if (can_erase)
@@ -95,15 +94,15 @@ bool SyncMetricStorage::Collect(CollectorHandle *collector,
   }
 
 #ifdef OPENTELEMETRY_HAVE_METRICS_BOUND_INSTRUMENTS_PREVIEW
-  // Rotate dirty bound entries: under each entry's own spinlock, swap out the
+  // Rotate dirty bound entries: under each entry's own mutex, swap out the
   // current aggregation and merge it into delta_metrics so bound + unbound
   // writes for the same post-filter attribute set produce one datapoint.
   for (auto &entry : entry_snapshot)
   {
     std::unique_ptr<Aggregation> rotated;
     MetricAttributes attrs_copy;
     {
-      std::lock_guard<opentelemetry::common::SpinLockMutex> g(entry->lock_);
+      std::lock_guard<std::mutex> g(entry->lock_);
       if (!entry->dirty_)
       {
         continue;
@@ -160,7 +159,7 @@ bool SyncMetricStorage::Collect(CollectorHandle *collector,
       // satisfy the documented invariant on dirty_.
       bool entry_dirty = false;
       {
-        std::lock_guard<opentelemetry::common::SpinLockMutex> g(it->second->lock_);
+        std::lock_guard<std::mutex> g(it->second->lock_);
         entry_dirty = it->second->dirty_;
       }
       if (entry_dirty)
@@ -228,7 +227,7 @@ void SyncMetricStorage::BoundEntry::RecordLong(int64_t value) noexcept
         "is not long");
     return;
   }
-  std::lock_guard<opentelemetry::common::SpinLockMutex> guard(lock_);
+  std::lock_guard<std::mutex> guard(lock_);
   current_->Aggregate(value);
   dirty_ = true;
 }
@@ -242,7 +241,7 @@ void SyncMetricStorage::BoundEntry::RecordDouble(double value) noexcept
         "is not double");
     return;
   }
-  std::lock_guard<opentelemetry::common::SpinLockMutex> guard(lock_);
+  std::lock_guard<std::mutex> guard(lock_);
   current_->Aggregate(value);
   dirty_ = true;
 }

sdk/src/metrics/state/temporal_metric_storage.cc

@@ -9,7 +9,6 @@
 #include <utility>
 #include <vector>
 
-#include "opentelemetry/common/spin_lock_mutex.h"
 #include "opentelemetry/common/timestamp.h"
 #include "opentelemetry/nostd/function_ref.h"
 #include "opentelemetry/nostd/span.h"
@@ -46,7 +45,7 @@ bool TemporalMetricStorage::buildMetrics(CollectorHandle *collector,
                                          const std::shared_ptr<AttributesHashMap> &delta_metrics,
                                          nostd::function_ref<bool(MetricData)> callback) noexcept
 {
-  std::lock_guard<opentelemetry::common::SpinLockMutex> guard(lock_);
+  std::lock_guard<std::mutex> guard(lock_);
   AggregationTemporality aggregation_temporarily =
       collector->GetAggregationTemporality(instrument_descriptor_.type_);
   // Per OTel spec (issue #4062): the start_ts for the first delta collection