From 9f752e58143dee9627215c8139b8d88ee674a636 Mon Sep 17 00:00:00 2001
From: duncanpo <dpo@mathworks.com>
Date: Tue, 30 Jan 2024 10:55:23 -0500
Subject: [PATCH] Asynchronous metrics example #78, #79

---
 examples/metrics/README.md               | 17 +++++--
 examples/metrics/async_metrics_example.m | 63 ++++++++++++++++++++++++
 test/tmetrics.m                          |  8 ---
 3 files changed, 77 insertions(+), 11 deletions(-)
 create mode 100644 examples/metrics/async_metrics_example.m

diff --git a/examples/metrics/README.md b/examples/metrics/README.md
index 3b65069..d604cec 100644
--- a/examples/metrics/README.md
+++ b/examples/metrics/README.md
@@ -1,10 +1,21 @@
 # Metrics Example
-This example shows how to emit OpenTelemetry metrics from MATLAB. It uses all 3 synchronous instruments counter, updowncounter, and histogram.
+There are two examples in this directory, metrics\_example and async\_metrics\_example.
+
+## metrics\_example
+This example shows how to emit OpenTelemetry synchronous metrics from MATLAB. It uses all 3 synchronous instruments counter, updowncounter, and histogram.
 * At the beginning of the first run, initialization is necessary to create and store a global meter provider.
 * The example then enters a loop and at each iteration updates all 3 instruments. The metrics will then be exported periodically at a fixed time interval.
 
-## Running the Example
+## async\_metrics\_example
+This example shows how to emit OpenTelemetry asynchronous metrics from MATLAB. Is uses all 3 asynchronous instruments observable counter, observable
+updowncounter, and obervable gauge.
+* Initialization is first done by creating and storing a global meter provider, and specifying a data export interval and timeout.
+* The asynchronous instruments are then created, passing in their respective callback functions.
+* The example then pauses for 100 seconds, allowing the asynchronous instruments to periodically fetch and export their measurements.
+* Finally, the global meter provider is shut down to stop any further data exports.
+
+## Running the Examples
 1. Start an instance of [OpenTelemetry Collector](https://github.com/open-telemetry/opentelemetry-collector).
 2. Start MATLAB. 
 3. Ensure the installation directory of OpenTelemetry-matlab is on the MATLAB path.
-4. Run metrics_example.
+4. Run metrics\_example or async\_metrics\_example.
diff --git a/examples/metrics/async_metrics_example.m b/examples/metrics/async_metrics_example.m
new file mode 100644
index 0000000..e4fa3b5
--- /dev/null
+++ b/examples/metrics/async_metrics_example.m
@@ -0,0 +1,63 @@
+function async_metrics_example
+% This example creates 3 asynchronous metric instruments including an 
+% observable counter, an observable updowncounter, and an observable gauge. 
+
+% Copyright 2024 The MathWorks, Inc.
+
+% initialize meter provider
+initMetrics;
+
+% create meter and instruments
+m = opentelemetry.metrics.getMeter("async_metrics_example");
+c = createObservableCounter(m, @counter_callback, "observable_counter"); %#ok<*NASGU>
+u = createObservableUpDownCounter(m, @updowncounter_callback, "observable_updowncounter");
+g = createObservableGauge(m, @gauge_callback, "observable_gauge"); 
+iterations = 20;    % number of iterations
+pause(iterations*5);
+
+% clean up
+cleanupMetrics;
+end
+
+
+function initMetrics
+% set up global MeterProvider
+exp = opentelemetry.exporters.otlp.defaultMetricExporter();
+reader = opentelemetry.sdk.metrics.PeriodicExportingMetricReader(exp, ...
+    "Interval", seconds(5), "Timeout", seconds(2.5));  % exports every 5 seconds
+mp = opentelemetry.sdk.metrics.MeterProvider(reader);
+setMeterProvider(mp);
+end
+
+function cleanupMetrics
+mp = opentelemetry.metrics.Provider.getMeterProvider();
+opentelemetry.sdk.common.Cleanup.shutdown(mp);   % shutdown
+end
+
+function result = counter_callback()
+persistent value
+if isempty(value)
+    value = 0;
+else
+    value = value + randi(10);  % increment between 1 to 10
+end
+result = opentelemetry.metrics.ObservableResult;
+result = result.observe(value);
+end
+
+function result = updowncounter_callback()
+persistent value
+if isempty(value)
+    value = 0;
+else
+    value = value + randi([-5 5]);  % increment between -5 to 5
+end
+result = opentelemetry.metrics.ObservableResult;
+result = result.observe(value);
+end
+
+function result = gauge_callback()
+s = second(datetime("now"));    % get the current second of the minute
+result = opentelemetry.metrics.ObservableResult;
+result = result.observe(s);
+end
\ No newline at end of file
diff --git a/test/tmetrics.m b/test/tmetrics.m
index a9342ca..a103218 100644
--- a/test/tmetrics.m
+++ b/test/tmetrics.m
@@ -612,10 +612,6 @@ function testAsynchronousInstrumentAnonymousCallback(testCase, create_async, dat
 
         function testAsynchronousInstrumentMultipleCallbacks(testCase, create_async, datapoint_name)
             % Observable counter with more than one callbacks
-
-            testCase.assumeTrue(false, ...
-                "Disabled due to sporadic failures.");
-
             countername = "bar";
             
             p = opentelemetry.sdk.metrics.MeterProvider(testCase.ShortIntervalReader);
@@ -653,10 +649,6 @@ function testAsynchronousInstrumentMultipleCallbacks(testCase, create_async, dat
 
         function testAsynchronousInstrumentRemoveCallback(testCase, create_async)
             % removeCallback method
-
-            testCase.assumeTrue(false, ...
-                "Disabled due to sporadic failures.");
-
             callback = @callbackNoAttributes;
 
             p = opentelemetry.sdk.metrics.MeterProvider(testCase.ShortIntervalReader);