Remove deprecated extension functions

I want to remove these functions from the Rust extension, but if the
Ruby gem still calls them, that would cause a new error on the next
extension update.

These functions already did nothing anymore in the Rust extension,
so not calling the extension functions loses no functionality. I did not
remove the Ruby methods, because people may still call them and we
should only remove methods in major releases.

Move the deprecation warnings to the Ruby gem and remove calls to the
extension functions.

- Part of appsignal/appsignal-agent#425
- Deprecations logged in
  #667

.changesets/deprecate-set_host_guage-and-set_process_gauge-helper-methods.md

@@ -0,0 +1,6 @@
+---
+bump: "patch"
+type: "deprecate"
+---
+
+Deprecate the `Appsignal.set_host_guage` and `Appsignal.set_process_gauge` helper methods in the Ruby gem. These methods would already log deprecation warnings in the `appsignal.log` file, but now also as a Ruby warning. These methods will be removed in the next major version. These methods already did not report any metrics, and still do not.

ext/appsignal_extension.c

@@ -759,28 +759,6 @@ static VALUE set_gauge(VALUE self, VALUE key, VALUE value, VALUE tags) {
   return Qnil;
 }
 
-static VALUE set_host_gauge(VALUE self, VALUE key, VALUE value) {
-  Check_Type(key, T_STRING);
-  Check_Type(value, T_FLOAT);
-
-  appsignal_set_host_gauge(
-      make_appsignal_string(key),
-      NUM2DBL(value)
-  );
-  return Qnil;
-}
-
-static VALUE set_process_gauge(VALUE self, VALUE key, VALUE value) {
-  Check_Type(key, T_STRING);
-  Check_Type(value, T_FLOAT);
-
-  appsignal_set_process_gauge(
-      make_appsignal_string(key),
-      NUM2DBL(value)
-  );
-  return Qnil;
-}
-
 static VALUE increment_counter(VALUE self, VALUE key, VALUE count, VALUE tags) {
   appsignal_data_t* tags_data;
 
@@ -941,8 +919,6 @@ void Init_appsignal_extension(void) {
 
   // Metrics
   rb_define_singleton_method(Extension, "set_gauge",              set_gauge,              3);
-  rb_define_singleton_method(Extension, "set_host_gauge",         set_host_gauge,         2);
-  rb_define_singleton_method(Extension, "set_process_gauge",      set_process_gauge,      2);
   rb_define_singleton_method(Extension, "increment_counter",      increment_counter,      3);
   rb_define_singleton_method(Extension, "add_distribution_value", add_distribution_value, 3);
 }

lib/appsignal/extension/jruby.rb

@@ -71,12 +71,6 @@ def self.lib_extension
         attach_function :appsignal_set_gauge,
           [:appsignal_string, :double, :pointer],
           :void
-        attach_function :appsignal_set_host_gauge,
-          [:appsignal_string, :double],
-          :void
-        attach_function :appsignal_set_process_gauge,
-          [:appsignal_string, :double],
-          :void
         attach_function :appsignal_increment_counter,
           [:appsignal_string, :double, :pointer],
           :void
@@ -319,14 +313,6 @@ def set_gauge(key, value, tags)
         appsignal_set_gauge(make_appsignal_string(key), value, tags.pointer)
       end
 
-      def set_host_gauge(key, value)
-        appsignal_set_host_gauge(make_appsignal_string(key), value)
-      end
-
-      def set_process_gauge(key, value)
-        appsignal_set_process_gauge(make_appsignal_string(key), value)
-      end
-
       def increment_counter(key, value, tags)
         appsignal_increment_counter(make_appsignal_string(key), value, tags.pointer)
       end

lib/appsignal/helpers/metrics.rb

@@ -14,18 +14,20 @@ def set_gauge(key, value, tags = {})
           .warn("Gauge value #{value} for key '#{key}' is too big")
       end
 
-      def set_host_gauge(key, value)
-        Appsignal::Extension.set_host_gauge(key.to_s, value.to_f)
-      rescue RangeError
-        Appsignal.logger
-          .warn("Host gauge value #{value} for key '#{key}' is too big")
+      def set_host_gauge(_key, _value)
+        Appsignal::Utils::DeprecationMessage.message \
+          "The `set_host_gauge` method has been deprecated. " \
+            "Calling this method has no effect. " \
+            "Please remove method call in the following file to remove " \
+            "this message.\n#{caller.first}"
       end
 
-      def set_process_gauge(key, value)
-        Appsignal::Extension.set_process_gauge(key.to_s, value.to_f)
-      rescue RangeError
-        Appsignal.logger
-          .warn("Process gauge value #{value} for key '#{key}' is too big")
+      def set_process_gauge(_key, _value)
+        Appsignal::Utils::DeprecationMessage.message \
+          "The `set_process_gauge` method has been deprecated. " \
+            "Calling this method has no effect. " \
+            "Please remove method call in the following file to remove " \
+            "this message.\n#{caller.first}"
       end
 
       def increment_counter(key, value = 1.0, tags = {})

spec/lib/appsignal_spec.rb

@@ -553,46 +553,46 @@
       end
 
       describe ".set_host_gauge" do
-        it "should call set_host_gauge on the extension with a string key and float" do
-          expect(Appsignal::Extension).to receive(:set_host_gauge).with("key", 0.1)
-          Appsignal.set_host_gauge("key", 0.1)
+        let(:err_stream) { std_stream }
+        let(:stderr) { err_stream.read }
+        let(:log_stream) { StringIO.new }
+        let(:logs) { log_contents(log_stream) }
+        let(:deprecation_message) do
+          "The `set_host_gauge` method has been deprecated. " \
+            "Calling this method has no effect. " \
+            "Please remove method call in the following file to remove " \
+            "this message."
         end
-
-        it "should call set_host_gauge on the extension with a symbol key and int" do
-          expect(Appsignal::Extension).to receive(:set_host_gauge).with("key", 1.0)
-          Appsignal.set_host_gauge(:key, 1)
+        before do
+          Appsignal.logger = test_logger(log_stream)
+          capture_std_streams(std_stream, err_stream) { Appsignal.set_host_gauge("key", 0.1) }
         end
 
-        it "should not raise an exception when out of range" do
-          expect(Appsignal::Extension).to receive(:set_host_gauge).with("key",
-            10).and_raise(RangeError)
-          expect(Appsignal.logger).to receive(:warn)
-            .with("Host gauge value 10 for key 'key' is too big")
-          expect do
-            Appsignal.set_host_gauge("key", 10)
-          end.to_not raise_error
+        it "logs a deprecation warning" do
+          expect(stderr).to include("appsignal WARNING: #{deprecation_message}")
+          expect(logs).to include(deprecation_message)
         end
       end
 
       describe ".set_process_gauge" do
-        it "should call set_process_gauge on the extension with a string key and float" do
-          expect(Appsignal::Extension).to receive(:set_process_gauge).with("key", 0.1)
-          Appsignal.set_process_gauge("key", 0.1)
+        let(:err_stream) { std_stream }
+        let(:stderr) { err_stream.read }
+        let(:log_stream) { StringIO.new }
+        let(:logs) { log_contents(log_stream) }
+        let(:deprecation_message) do
+          "The `set_process_gauge` method has been deprecated. " \
+            "Calling this method has no effect. " \
+            "Please remove method call in the following file to remove " \
+            "this message."
         end
-
-        it "should call set_process_gauge on the extension with a symbol key and int" do
-          expect(Appsignal::Extension).to receive(:set_process_gauge).with("key", 1.0)
-          Appsignal.set_process_gauge(:key, 1)
+        before do
+          Appsignal.logger = test_logger(log_stream)
+          capture_std_streams(std_stream, err_stream) { Appsignal.set_process_gauge("key", 0.1) }
         end
 
-        it "should not raise an exception when out of range" do
-          expect(Appsignal::Extension).to receive(:set_process_gauge).with("key",
-            10).and_raise(RangeError)
-          expect(Appsignal.logger).to receive(:warn)
-            .with("Process gauge value 10 for key 'key' is too big")
-          expect do
-            Appsignal.set_process_gauge("key", 10)
-          end.to_not raise_error
+        it "logs a deprecation warning" do
+          expect(stderr).to include("appsignal WARNING: #{deprecation_message}")
+          expect(logs).to include(deprecation_message)
         end
       end