handle the dot between prefix and key automatically

README.md

@@ -45,7 +45,7 @@ using namespace Statsd;
 
 int main() {
     // Define the client on localhost, with port 8080, using a prefix and a batching size of 20 bytes
-    StatsdClient client{ "127.0.0.1", 8080, "myPrefix.", 20 };
+    StatsdClient client{ "127.0.0.1", 8080, "myPrefix", 20 };
 
     // Increment the metric "coco"
     client.increment("coco");
@@ -85,7 +85,7 @@ struct MyApp {
         m_client.count("bar", 3);
     }
 private:
-    StatsdClient m_client{"localhost", 8125, "foo."};
+    StatsdClient m_client{"localhost", 8125, "foo"};
 };
 
 int main() {
@@ -110,12 +110,12 @@ using namespace Statsd;
 int main()
 {
     // Define the client on localhost, with port 8080, using a prefix and a batching size of 20 bytes
-    StatsdClient client{ "127.0.0.1", 8080, "myPrefix.", 20 };
+    StatsdClient client{ "127.0.0.1", 8080, "myPrefix", 20 };
 
     client.increment("coco");
 
     // Set a new configuration, using a different port and a different prefix
-    client.setConfig("127.0.0.1", 8000, "anotherPrefix.");
+    client.setConfig("127.0.0.1", 8000, "anotherPrefix");
 
     client.decrement("kiki");
 }

include/cpp-statsd-client/StatsdClient.hpp

@@ -17,6 +17,12 @@ namespace Statsd {
  * This is the Statsd client, exposing the classic methods
  * and relying on a UDP sender for the actual sending.
  *
+ * The prefix for a stat is provided once at construction or
+ * on reconfiguring the client. The separator character '.'
+ * is automatically inserted between the prefix and the stats
+ * key, therefore you should neither append one to the prefix
+ * nor prepend one to the key
+ *
  * The sampling frequency can be input, as well as the
  * batching size. The latter is the optional limit in
  * number of bytes a batch of stats can be before it is
@@ -86,11 +92,21 @@ class StatsdClient {
     mutable std::mt19937 m_randomEngine;
 };
 
+namespace detail {
+std::string sanitizePrefix(std::string prefix) {
+    // For convenience we provide the dot when generating the stat message
+    if (!prefix.empty() && prefix.back() == '.') {
+        prefix.pop_back();
+    }
+    return prefix;
+}
+}  // namespace detail
+
 inline StatsdClient::StatsdClient(const std::string& host,
                                   const uint16_t port,
                                   const std::string& prefix,
                                   const uint64_t batchsize) noexcept
-    : m_prefix(prefix), m_sender(new UDPSender{host, port, batchsize}) {
+    : m_prefix(detail::sanitizePrefix(prefix)), m_sender(new UDPSender{host, port, batchsize}) {
     // Initialize the random generator to be used for sampling
     seed();
 }
@@ -99,7 +115,7 @@ inline void StatsdClient::setConfig(const std::string& host,
                                     const uint16_t port,
                                     const std::string& prefix,
                                     const uint64_t batchsize) noexcept {
-    m_prefix = prefix;
+    m_prefix = detail::sanitizePrefix(prefix);
     m_sender.reset(new UDPSender(host, port, batchsize));
 }
 
@@ -150,18 +166,26 @@ inline void StatsdClient::send(const std::string& key,
     }
 
     // Prepare the buffer and include the sampling rate if it's not 1.f
+    const bool needs_dot = !m_prefix.empty() && !key.empty();
     std::string buffer(256, '\0');
     int string_len = -1;
     if (isFrequencyOne) {
         // Sampling rate is 1.0f, no need to specify it
-        string_len = std::snprintf(
-            &buffer.front(), buffer.size(), "%s%s:%d|%s", m_prefix.c_str(), key.c_str(), value, type.c_str());
+        string_len = std::snprintf(&buffer.front(),
+                                   buffer.size(),
+                                   "%s%s%s:%d|%s",
+                                   m_prefix.c_str(),
+                                   needs_dot ? "." : "",
+                                   key.c_str(),
+                                   value,
+                                   type.c_str());
     } else {
         // Sampling rate is different from 1.0f, hence specify it
         string_len = std::snprintf(&buffer.front(),
                                    buffer.size(),
-                                   "%s%s:%d|%s|@%.2f",
+                                   "%s%s%s:%d|%s|@%.2f",
                                    m_prefix.c_str(),
+                                   needs_dot ? "." : "",
                                    key.c_str(),
                                    value,
                                    type.c_str(),

tests/testStatsdClient.cpp

@@ -57,12 +57,23 @@ void testReconfigure() {
         throw std::runtime_error("Incorrect stat received");
     }
 
-    client.setConfig("localhost", 8125, "second.");
+    client.setConfig("localhost", 8125, "second");
     client.send("bar", 1, "c", 1.f);
     if (server.receive() != "second.bar:1|c") {
         throw std::runtime_error("Incorrect stat received");
     }
 
+    client.setConfig("localhost", 8125, "");
+    client.send("third.baz", 1, "c", 1.f);
+    if (server.receive() != "third.baz:1|c") {
+        throw std::runtime_error("Incorrect stat received");
+    }
+
+    client.send("", 1, "c", 1.f);
+    if (server.receive() != ":1|c") {
+        throw std::runtime_error("Incorrect stat received");
+    }
+
     // TODO: test what happens with the batching after resolving the question about incomplete
     //  batches being dropped vs sent on reconfiguring
 }
@@ -90,7 +101,7 @@ void testSendRecv(uint64_t batchSize) {
         throwOnError(client);
         expected.emplace_back("sendRecv.kiki:-1|c");
 
-        // Adjusts "toto" by +3
+        // Adjusts "toto" by +2
         client.seed(19);  // this seed gets a hit on the first call
         client.count("toto", 2, 0.1f);
         throwOnError(client);
@@ -112,9 +123,9 @@ void testSendRecv(uint64_t batchSize) {
         expected.emplace_back("sendRecv.myTiming:2|ms|@0.10");
 
         // Send a metric explicitly
-        client.send("tutu", 4, "c", 2.0f);
+        client.send("tutu", 241, "c", 2.0f);
         throwOnError(client);
-        expected.emplace_back("sendRecv.tutu:4|c");
+        expected.emplace_back("sendRecv.tutu:241|c");
     }
 
     // Signal the mock server we are done