refactor: add OpentelemetryLogBuilder::labels (#61)

Co-authored-by: tison <wander4096@gmail.com>

src/append/opentelemetry.rs

@@ -70,7 +70,7 @@ impl OpentelemetryLogBuilder {
     /// Default to [`Grpc`].
     ///
     /// [`Grpc`]: OpentelemetryWireProtocol::Grpc
-    pub fn with_protocol(mut self, protocol: OpentelemetryWireProtocol) -> Self {
+    pub fn protocol(mut self, protocol: OpentelemetryWireProtocol) -> Self {
         self.protocol = match protocol {
             OpentelemetryWireProtocol::Grpc => Protocol::Grpc,
             OpentelemetryWireProtocol::HttpBinary => Protocol::HttpBinary,
@@ -79,8 +79,8 @@ impl OpentelemetryLogBuilder {
         self
     }
 
-    /// Add a label to the resource.
-    pub fn add_label(
+    /// Append a label to the resource.
+    pub fn label(
         mut self,
         key: impl Into<Cow<'static, str>>,
         value: impl Into<Cow<'static, str>>,
@@ -89,6 +89,17 @@ impl OpentelemetryLogBuilder {
         self
     }
 
+    /// Append multiple labels to the resource.
+    pub fn labels<K, V>(mut self, labels: impl IntoIterator<Item = (K, V)>) -> Self
+    where
+        K: Into<Cow<'static, str>>,
+        V: Into<Cow<'static, str>>,
+    {
+        self.labels
+            .extend(labels.into_iter().map(|(k, v)| (k.into(), v.into())));
+        self
+    }
+
     /// Build the [`OpentelemetryLog`] appender.
     pub fn build(self) -> Result<OpentelemetryLog, opentelemetry::logs::LogError> {
         let OpentelemetryLogBuilder {

src/layout/kv.rs

@@ -13,6 +13,8 @@
 // limitations under the License.
 
 /// A helper struct to format log's key-value pairs.
+///
+/// This is useful when you want to display log's key-value pairs in a log message.
 pub struct KvDisplay<'kvs> {
     kv: &'kvs dyn log::kv::Source,
 }
@@ -47,6 +49,8 @@ impl<'a, 'kvs> log::kv::Visitor<'kvs> for KvWriter<'a, 'kvs> {
 }
 
 /// A helper to collect log's key-value pairs.
+/// 
+/// This is useful when you want to collect log's key-value pairs for further processing.
 pub fn collect_kvs(kv: &dyn log::kv::Source) -> Vec<(String, String)> {
     let mut collector = KvCollector { kv: Vec::new() };
     kv.visit(&mut collector).ok();