feat: add client.sent property (#7)

README.md

@@ -116,6 +116,12 @@ The client is not closed when the `error` event is emitted.
 The `finish` event is emitted after the `client.end()` method has been
 called, and all data has been flushed to the underlying system.
 
+### `client.sent`
+
+An integer indicating the number of events (spans, transactions, or errors)
+sent by the client. An event is considered sent when the HTTP request
+used to transmit it have ended.
+
 ### `client.sendSpan(span[, callback])`
 
 Send a span to the APM Server.

index.js

@@ -46,6 +46,8 @@ function Client (opts) {
     if (this._writableState.ending === false) this.destroy()
   }
 
+  this._received = 0 // number of events given to the client for reporting
+  this.sent = 0 // number of events written to the socket
   this._active = false
   this._destroyed = false
   this._onflushed = null
@@ -90,6 +92,7 @@ Client.prototype._write = function (obj, enc, cb) {
       this._chopper.chop(cb)
     }
   } else {
+    this._received++
     this._stream.write(obj, cb)
   }
 }
@@ -205,6 +208,7 @@ function onStream (opts, client, onerror) {
       //    would not get it here as the internal error listener would have
       //    been removed and the stream would throw the error instead
 
+      client.sent = client._received
       client._active = false
       if (client._onflushed) {
         client._onflushed()

test/test.js

@@ -469,6 +469,41 @@ test('client.end(callback)', function (t) {
   })
 })
 
+test('client.sent', function (t) {
+  t.plan(8)
+  let client
+  let requests = 0
+  const server = APMServer(function (req, res) {
+    requests++
+    t.equal(client.sent, 3 * (requests - 1))
+    req.resume()
+    req.on('end', function () {
+      t.equal(client.sent, 3 * requests)
+      res.end()
+      if (requests === 2) {
+        server.close()
+        t.end()
+      }
+    })
+  }).client(function (_client) {
+    client = _client
+    client.sendError({foo: 42})
+    client.sendSpan({foo: 42})
+    client.sendTransaction({foo: 42})
+    t.equal(client.sent, 0)
+    client.flush(function () {
+      t.equal(client.sent, 3)
+      client.sendError({foo: 42})
+      client.sendSpan({foo: 42})
+      client.sendTransaction({foo: 42})
+      t.equal(client.sent, 3)
+      client.flush(function () {
+        t.equal(client.sent, 6)
+      })
+    })
+  })
+})
+
 /**
  * Side effects
  */