mathworks · duncanpo · Jan 26, 2024 · Dec 1, 2023 · Dec 4, 2023 · Dec 4, 2023
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -165,6 +165,7 @@ endif()
 
 set(OPENTELEMETRY_PROXY_LIBRARY_NAME "OtelMatlabProxy")
 
+find_package(Matlab REQUIRED)
 find_package(Protobuf REQUIRED)
 find_package(nlohmann_json REQUIRED)
 if(WIN32)
@@ -196,7 +197,7 @@ set(TRACE_SDK_INCLUDE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/sdk/trace/include)
 set(METRICS_SDK_INCLUDE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/sdk/metrics/include)
 set(COMMON_SDK_INCLUDE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/sdk/common/include)
 set(OTLP_EXPORTER_INCLUDE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/exporters/otlp/include)
-set(OPENTELEMETRY_PROXY_INCLUDE_DIRS ${CMAKE_CURRENT_SOURCE_DIR} ${TRACE_API_INCLUDE_DIR} ${METRICS_API_INCLUDE_DIR} ${CONTEXT_API_INCLUDE_DIR} ${BAGGAGE_API_INCLUDE_DIR} ${COMMON_API_INCLUDE_DIR} ${TRACE_SDK_INCLUDE_DIR} ${METRICS_SDK_INCLUDE_DIR} ${COMMON_SDK_INCLUDE_DIR} ${OTLP_EXPORTER_INCLUDE_DIR} ${OTEL_CPP_PREFIX}/include)
+set(OPENTELEMETRY_PROXY_INCLUDE_DIRS ${CMAKE_CURRENT_SOURCE_DIR} ${TRACE_API_INCLUDE_DIR} ${METRICS_API_INCLUDE_DIR} ${CONTEXT_API_INCLUDE_DIR} ${BAGGAGE_API_INCLUDE_DIR} ${COMMON_API_INCLUDE_DIR} ${TRACE_SDK_INCLUDE_DIR} ${METRICS_SDK_INCLUDE_DIR} ${COMMON_SDK_INCLUDE_DIR} ${OTLP_EXPORTER_INCLUDE_DIR} ${OTEL_CPP_PREFIX}/include ${Matlab_INCLUDE_DIRS})
 
 set(OPENTELEMETRY_PROXY_FACTORY_CLASS_NAME OtelMatlabProxyFactory)
 set(OPENTELEMETRY_PROXY_FACTORY_SOURCES_DIR ${CMAKE_CURRENT_SOURCE_DIR})
@@ -222,6 +223,9 @@ set(OPENTELEMETRY_PROXY_SOURCES
     ${METRICS_API_SOURCE_DIR}/UpDownCounterProxy.cpp
     ${METRICS_API_SOURCE_DIR}/HistogramProxy.cpp
     ${METRICS_API_SOURCE_DIR}/SynchronousInstrumentProxyFactory.cpp
+    ${METRICS_API_SOURCE_DIR}/MeasurementFetcher.cpp
+    ${METRICS_API_SOURCE_DIR}/AsynchronousInstrumentProxy.cpp
+    ${METRICS_API_SOURCE_DIR}/AsynchronousInstrumentProxyFactory.cpp
     ${CONTEXT_API_SOURCE_DIR}/TextMapPropagatorProxy.cpp
     ${CONTEXT_API_SOURCE_DIR}/CompositePropagatorProxy.cpp
     ${CONTEXT_API_SOURCE_DIR}/TextMapCarrierProxy.cpp
@@ -295,7 +299,7 @@ set(OTEL_CPP_LINK_LIBRARIES ${OTEL_CPP_PREFIX}/lib/${CMAKE_STATIC_LIBRARY_PREFIX
 	${OTEL_CPP_PREFIX}/lib/${CMAKE_STATIC_LIBRARY_PREFIX}opentelemetry_version${CMAKE_STATIC_LIBRARY_SUFFIX}
 	${OTEL_CPP_PREFIX}/lib/${CMAKE_STATIC_LIBRARY_PREFIX}opentelemetry_logs${CMAKE_STATIC_LIBRARY_SUFFIX}
 	${OTEL_CPP_PREFIX}/lib/${CMAKE_STATIC_LIBRARY_PREFIX}opentelemetry_metrics${CMAKE_STATIC_LIBRARY_SUFFIX}
-	${Protobuf_LIBRARIES})
+	${Protobuf_LIBRARIES} ${Matlab_MEX_LIBRARY})
 if(WITH_OTLP_HTTP)
     set(OTEL_CPP_LINK_LIBRARIES ${OTEL_CPP_LINK_LIBRARIES} ${OTEL_CPP_PREFIX}/lib/${CMAKE_STATIC_LIBRARY_PREFIX}opentelemetry_exporter_otlp_http${CMAKE_STATIC_LIBRARY_SUFFIX}
 	    ${OTEL_CPP_PREFIX}/lib/${CMAKE_STATIC_LIBRARY_PREFIX}opentelemetry_exporter_otlp_http_client${CMAKE_STATIC_LIBRARY_SUFFIX}

diff --git a/README.md b/README.md
@@ -4,7 +4,7 @@
 MATLAB&reg; interface to [OpenTelemetry&trade;](https://opentelemetry.io/), based on the [OpenTelemetry Specification](https://opentelemetry.io/docs/reference/specification/). OpenTelemetry is an observability framework for creating and managing telemetry data, such as traces, metrics, and logs. This data can then be sent to an observability back-end for monitoring, alerts, and analysis. 
 
 ### Status
-- Currently only tracing and metrics (synchronous instruments) are supported. Asynchronous metrics instruments and logs will be in the future.
+- Currently only tracing and metrics are supported. Logs will be in the future.
 - View class in metrics is only partially supported. The properties **Aggregation** and **AllowedAttributes** are not yet supported. 
 - This package is supported and has been tested on Windows&reg;, Linux&reg;, and macOS.
 

diff --git a/api/metrics/+opentelemetry/+metrics/AsynchronousInstrument.m b/api/metrics/+opentelemetry/+metrics/AsynchronousInstrument.m
@@ -0,0 +1,81 @@
+classdef AsynchronousInstrument < handle
+    % Base class inherited by all asynchronous instruments
+
+    % Copyright 2023-2024 The MathWorks, Inc.
+
+    properties (SetAccess=immutable)
+        Name        (1,1) string    % Instrument name
+        Description (1,1) string    % Description of instrument
+        Unit        (1,1) string    % Measurement unit
+    end
+
+    properties (SetAccess=private)
+        Callbacks     % Callback function, called at each data export
+    end
+
+    properties (Access=private)
+        Proxy   % Proxy object to interface C++ code
+    end
+
+    methods (Access=protected)
+        function obj = AsynchronousInstrument(proxy, name, description, unit, callback)
+            obj.Proxy = proxy;
+            obj.Name = name;
+            obj.Description = description;
+            obj.Unit = unit;
+            obj.Callbacks = callback;
+        end
+
+    end
+
+    methods
+        function addCallback(obj, callback)
+            % ADDCALLBACK   Add a callback function
+            %    ADDCALLBACK(INST, CALLBACK) adds a callback function to
+            %    collect metrics at every export. CALLBACK is specified as a 
+            %    function handle, and must accept no input and return one
+            %    output of type opentelemetry.metrics.ObservableResult.
+            %
+            %    See also REMOVECALLBACK, OPENTELEMETRY.METRICS.OBSERVABLERESULT
+            if isa(callback, "function_handle")
+                obj.Proxy.addCallback(callback);
+                % append to Callbacks property
+                if isempty(obj.Callbacks)
+                    obj.Callbacks = callback;
+                elseif isa(obj.Callbacks, "function_handle")
+                    obj.Callbacks = {obj.Callbacks, callback};
+                else
+                    obj.Callbacks = [obj.Callbacks, {callback}];
+                end
+            end 
+        end
+
+        function removeCallback(obj, callback)
+            % REMOVECALLBACK   Remove a callback function
+            %    REMOVECALLBACK(INST, CALLBACK) removes a callback function 
+            %    CALLBACK specified as a function handle.
+            %
+            %    See also ADDCALLBACK
+            if isa(callback, "function_handle") && ~isempty(obj.Callbacks)
+                if iscell(obj.Callbacks)
+                    found = cellfun(@(x)isequal(x,callback), obj.Callbacks);
+                else   % scalar function handle
+                    found = isequal(obj.Callbacks, callback);
+                end
+                if sum(found) > 0
+                    idx = find(found,1);  % remove only the first match
+                    obj.Proxy.removeCallback(idx);
+                    % update Callback property
+                    if isa(obj.Callbacks, "function_handle")
+                        obj.Callbacks = [];
+                    else
+                        obj.Callbacks(idx) = [];  
+                        if isscalar(obj.Callbacks)   % if there is only one left, remove the cell
+                            obj.Callbacks = obj.Callbacks{1};
+                        end
+                    end
+                end
+            end
+        end
+    end
+end
diff --git a/api/metrics/+opentelemetry/+metrics/Meter.m b/api/metrics/+opentelemetry/+metrics/Meter.m
@@ -2,7 +2,7 @@
     % A Meter creates metric instruments, capturing measurements about a service at runtime. 
     % Meters are created from Meter Providers.
 
-    % Copyright 2023 The MathWorks, Inc.
+    % Copyright 2023-2024 The MathWorks, Inc.
 
     properties (SetAccess=immutable)
         Name    (1,1) string   % Meter name
@@ -29,7 +29,7 @@
 
     methods
 
-        function counter = createCounter(obj, ctname, ctdescription, ctunit)
+        function counter = createCounter(obj, name, description, unit)
             % CREATECOUNTER Create a counter
             %    C = CREATECOUNTER(M, NAME) creates a counter with the specified
             %    name. A counter's value can only increase but not
@@ -38,25 +38,24 @@
             %    C = CREATECOUNTER(M, NAME, DESCRIPTION, UNIT) also 
             %    specifies a description and a unit.
             %     
-            %    See also CREATEUPDOWNCOUNTER, CREATEHISTOGRAM
+            %    See also CREATEUPDOWNCOUNTER, CREATEHISTOGRAM,
+            %    CREATEOBSERVABLECOUNTER
             arguments
                 obj
-                ctname
-                ctdescription = ""
-                ctunit = ""
+                name
+                description = ""
+                unit = ""
             end
-            import opentelemetry.common.mustBeScalarString
-            ctname = mustBeScalarString(ctname);
-            ctdescription = mustBeScalarString(ctdescription);
-            ctunit = mustBeScalarString(ctunit);
-            id = obj.Proxy.createCounter(ctname, ctdescription, ctunit);
+            [name, description, unit] = processSynchronousInputs(name, ...
+                description, unit);
+            id = obj.Proxy.createCounter(name, description, unit);
             CounterProxy = libmexclass.proxy.Proxy("Name", ...
                 "libmexclass.opentelemetry.CounterProxy", "ID", id);
-            counter = opentelemetry.metrics.Counter(CounterProxy, ctname, ctdescription, ctunit);
+            counter = opentelemetry.metrics.Counter(CounterProxy, name, description, unit);
         end
 
 
-        function updowncounter = createUpDownCounter(obj, ctname, ctdescription, ctunit)
+        function updowncounter = createUpDownCounter(obj, name, description, unit)
             % CREATEUPDOWNCOUNTER Create an UpDownCounter
             %    C = CREATEUPDOWNCOUNTER(M, NAME) creates an UpDownCounter 
             %    with the specified name. An UpDownCounter's value can
@@ -65,26 +64,25 @@
             %    C = CREATEUPDOWNCOUNTER(M, NAME, DESCRIPTION, UNIT) also 
             %    specifies a description and a unit.
             %     
-            %    See also CREATECOUNTER, CREATEHISTOGRAM
+            %    See also CREATECOUNTER, CREATEHISTOGRAM,
+            %    CREATEOBSERVABLEUPDOWNCOUNTER
             arguments
                 obj
-                ctname
-                ctdescription = ""
-                ctunit = ""
+                name
+                description = ""
+                unit = ""
             end
 
-            import opentelemetry.common.mustBeScalarString
-            ctname = mustBeScalarString(ctname);
-            ctdescription = mustBeScalarString(ctdescription);
-            ctunit = mustBeScalarString(ctunit);
-            id = obj.Proxy.createUpDownCounter(ctname, ctdescription, ctunit);
+            [name, description, unit] = processSynchronousInputs(name, ...
+                description, unit);
+            id = obj.Proxy.createUpDownCounter(name, description, unit);
             UpDownCounterProxy = libmexclass.proxy.Proxy("Name", ...
                 "libmexclass.opentelemetry.UpDownCounterProxy", "ID", id);
-            updowncounter = opentelemetry.metrics.UpDownCounter(UpDownCounterProxy, ctname, ctdescription, ctunit);
+            updowncounter = opentelemetry.metrics.UpDownCounter(UpDownCounterProxy, name, description, unit);
         end
 
 
-        function histogram = createHistogram(obj, hiname, hidescription, hiunit)
+        function histogram = createHistogram(obj, name, description, unit)
             % CREATEHISTOGRAM Create a histogram
             %    H = CREATEHISTOGRAM(M, NAME) creates a histogram with the specified
             %    name. A histogram aggregates values into bins. Bins can be
@@ -97,21 +95,126 @@
             %    OPENTELEMETRY.SDK.METRICS.VIEW
             arguments
                 obj
-                hiname
-                hidescription = ""
-                hiunit = ""
+                name
+                description = ""
+                unit = ""
             end
 
-            import opentelemetry.common.mustBeScalarString
-            hiname = mustBeScalarString(hiname);
-            hidescription = mustBeScalarString(hidescription);
-            hiunit = mustBeScalarString(hiunit);
-            id = obj.Proxy.createHistogram(hiname, hidescription, hiunit);
+            [name, description, unit] = processSynchronousInputs(name, ...
+                description, unit);
+            id = obj.Proxy.createHistogram(name, description, unit);
             HistogramProxy = libmexclass.proxy.Proxy("Name", ...
                 "libmexclass.opentelemetry.HistogramProxy", "ID", id);
-            histogram = opentelemetry.metrics.Histogram(HistogramProxy, hiname, hidescription, hiunit);
+            histogram = opentelemetry.metrics.Histogram(HistogramProxy, name, description, unit);
         end
 
-    end
-
+    	function obscounter = createObservableCounter(obj, callback, name, description, unit)
+            % CREATEOBSERVABLECOUNTER Create an observable counter
+            %    C = CREATEOBSERVABLECOUNTER(M, CALLBACK, NAME) creates an 
+            %    observable counter with the specified callback function 
+            %    and name. The callback function, specified as a 
+            %    function handle, must accept no input and return one
+            %    output of type opentelemetry.metrics.ObservableResult.
+            %    The counter's value can only increase but not decrease.
+            %
+            %    C = CREATEOBSERVABLECOUNTER(M, CALLBACK NAME, DESCRIPTION, UNIT) 
+            %    also specifies a description and a unit.
+            %     
+            %    See also OPENTELEMETRY.METRICS.OBSERVABLERESULT, 
+            %    CREATEOBSERVABLEUPDOWNCOUNTER, CREATEOBSERVABLEGAUGE, CREATECOUNTER
+            arguments
+                obj
+                callback
+                name
+                description = ""
+                unit = ""
+            end
+
+            [callback, name, description, unit] = processAsynchronousInputs(...
+                callback, name, description, unit);
+            id = obj.Proxy.createObservableCounter(name, description, unit, callback);
+            ObservableCounterproxy = libmexclass.proxy.Proxy("Name", ...
+                "libmexclass.opentelemetry.ObservableCounterProxy", "ID", id);
+            obscounter = opentelemetry.metrics.ObservableCounter(ObservableCounterproxy, name, description, unit, callback);
+        end
+
+        function obsudcounter = createObservableUpDownCounter(obj, callback, name, description, unit)
+            % CREATEOBSERVABLEUPDOWNCOUNTER Create an observable UpDownCounter
+            %    C = CREATEOBSERVABLEUPDOWNCOUNTER(M, CALLBACK, NAME) 
+            %    creates an observable UpDownCounter with the specified 
+            %    callback function and name. The callback function, 
+            %    specified as a function handle, must accept no input and 
+            %    return one output of type opentelemetry.metrics.ObservableResult.
+            %    The UpDownCounter's value can increase or decrease.
+            %
+            %    C = CREATEOBSERVABLEUPDOWNCOUNTER(M, CALLBACK, NAME, DESCRIPTION, UNIT) 
+            %    also specifies a description and a unit.
+            %     
+            %    See also OPENTELEMETRY.METRICS.OBSERVABLERESULT, 
+            %    CREATEOBSERVABLECOUNTER, CREATEOBSERVABLEGAUGE, CREATEUPDOWNCOUNTER
+            arguments
+                obj
+                callback
+                name
+                description = ""
+                unit = ""
+            end
+
+            [callback, name, description, unit] = processAsynchronousInputs(...
+                callback, name, description, unit);
+            id = obj.Proxy.createObservableUpDownCounter(name, description, unit, callback);
+            ObservableUpDownCounterproxy = libmexclass.proxy.Proxy("Name", ...
+                "libmexclass.opentelemetry.ObservableUpDownCounterProxy", "ID", id);
+            obsudcounter = opentelemetry.metrics.ObservableUpDownCounter(...
+                ObservableUpDownCounterproxy, name, description, unit, callback);
+        end
+
+        function obsgauge = createObservableGauge(obj, callback, name, description, unit)
+            % CREATEOBSERVABLEGAUGE Create an observable gauge
+            %    C = CREATEOBSERVABLEGAUGE(M, CALLBACK, NAME) creates an 
+            %    observable gauge with the specified callback function 
+            %    and name. The callback function, specified as a 
+            %    function handle, must accept no input and return one
+            %    output of type opentelemetry.metrics.ObservableResult.
+            %    A gauge's value can increase or decrease but it should 
+            %    never be summed in aggregation.
+            %
+            %    C = CREATEOBSERVABLEGAUGE(M, CALLBACK NAME, DESCRIPTION, UNIT) 
+            %    also specifies a description and a unit.
+            %     
+            %    See also OPENTELEMETRY.METRICS.OBSERVABLERESULT, 
+            %    CREATEOBSERVABLECOUNTER, CREATEOBSERVABLEUPDOWNCOUNTER
+            arguments
+                obj
+                callback
+                name
+                description = ""
+                unit = ""
+            end
+
+            [callback, name, description, unit] = processAsynchronousInputs(...
+                callback, name, description, unit);
+            id = obj.Proxy.createObservableGauge(name, description, unit, callback);
+            ObservableGaugeproxy = libmexclass.proxy.Proxy("Name", ...
+                "libmexclass.opentelemetry.ObservableGaugeProxy", "ID", id);
+            obsgauge = opentelemetry.metrics.ObservableGauge(...
+                ObservableGaugeproxy, name, description, unit, callback);
+        end
+    end    
+end
+
+function [name, description, unit] = processSynchronousInputs(name, ...
+    description, unit)
+import opentelemetry.common.mustBeScalarString
+name = mustBeScalarString(name);
+description = mustBeScalarString(description);
+unit = mustBeScalarString(unit);
+end
+
+function [callback, name, description, unit] = processAsynchronousInputs(...
+    callback, name, description, unit)
+[name, description, unit] = processSynchronousInputs(name, description, unit);
+if ~isa(callback, "function_handle")
+    callback = [];   % callback is invalid, set to empty double
+end
 end
diff --git a/api/metrics/+opentelemetry/+metrics/ObservableCounter.m b/api/metrics/+opentelemetry/+metrics/ObservableCounter.m
@@ -0,0 +1,17 @@
+classdef ObservableCounter < opentelemetry.metrics.AsynchronousInstrument
+    % ObservableCounter is an asynchronous counter that records its value
+    % via a callback and its value can only increase but not decrease
+
+    % Copyright 2023 The MathWorks, Inc.
+
+    methods (Access={?opentelemetry.metrics.Meter})
+
+        function obj = ObservableCounter(proxy, name, description, unit, callback)
+            % Private constructor. Use getObservableCounter method of Meter
+            % to create observable counters.
+            obj@opentelemetry.metrics.AsynchronousInstrument(proxy, name, ...
+                description, unit, callback);
+        end
+
+    end
+end
diff --git a/api/metrics/+opentelemetry/+metrics/ObservableGauge.m b/api/metrics/+opentelemetry/+metrics/ObservableGauge.m
@@ -0,0 +1,17 @@
+classdef ObservableGauge < opentelemetry.metrics.AsynchronousInstrument
+    % ObservableGauge is an asynchronous gauge that report its values via a
+    % callback and its value cannot be summed in aggregation.
+
+    % Copyright 2023 The MathWorks, Inc.
+
+    methods (Access={?opentelemetry.metrics.Meter})
+
+        function obj = ObservableGauge(proxy, name, description, unit, callback)
+            % Private constructor. Use getObservableGauge method of Meter
+            % to create observable gauges.
+            obj@opentelemetry.metrics.AsynchronousInstrument(proxy, name, ...
+                description, unit, callback);
+        end
+
+    end
+end