refactor: remove redudant PromStoreProtocolHandler::write (#3553)

refactor: remove redudant PromStoreProtocolHandler::write API and rename PromStoreProtocolHandler::write_fast to write

src/servers/src/export_metrics.rs

@@ -29,7 +29,7 @@ use snafu::{ensure, ResultExt};
 use tokio::time::{self, Interval};
 
 use crate::error::{InvalidExportMetricsConfigSnafu, Result, SendPromRemoteRequestSnafu};
-use crate::prom_store::snappy_compress;
+use crate::prom_store::{snappy_compress, to_grpc_row_insert_requests};
 use crate::query_handler::PromStoreProtocolHandlerRef;
 
 /// Use to export the metrics generated by greptimedb, encoded to Prometheus [RemoteWrite format](https://prometheus.io/docs/concepts/remote_write_spec/),
@@ -256,8 +256,19 @@ pub async fn write_system_metric_by_handler(
             filter.as_ref(),
             Timestamp::current_millis().value(),
         );
-        if let Err(e) = handler.write(request, ctx.clone(), false).await {
+
+        let (requests, samples) = match to_grpc_row_insert_requests(&request) {
+            Ok((requests, samples)) => (requests, samples),
+            Err(e) => {
+                error!(e; "Failed to convert gathered metrics to RowInsertRequests");
+                continue;
+            }
+        };
+
+        if let Err(e) = handler.write(requests, ctx.clone(), false).await {
             error!("report export metrics by handler failed, error {}", e);
+        } else {
+            crate::metrics::PROM_STORE_REMOTE_WRITE_SAMPLES.inc_by(samples as u64);
         }
     }
 }

src/servers/src/http/prom_store.rs

@@ -14,7 +14,7 @@
 
 use std::sync::Arc;
 
-use api::prom_store::remote::{ReadRequest, WriteRequest};
+use api::prom_store::remote::ReadRequest;
 use api::v1::RowInsertRequests;
 use axum::extract::{Query, RawBody, State};
 use axum::http::{header, HeaderValue, StatusCode};
@@ -75,13 +75,14 @@ pub async fn route_write_without_metric_engine(
         .with_label_values(&[db.as_str()])
         .start_timer();
 
-    let request = decode_remote_write_request(body).await?;
+    let (request, samples) = decode_remote_write_request(body).await?;
     // reject if physical table is specified when metric engine is disabled
     if params.physical_table.is_some() {
         return UnexpectedPhysicalTableSnafu {}.fail();
     }
 
     let output = handler.write(request, query_ctx, false).await?;
+    crate::metrics::PROM_STORE_REMOTE_WRITE_SAMPLES.inc_by(samples as u64);
     Ok((
         StatusCode::NO_CONTENT,
         write_cost_header_map(output.meta.cost),
@@ -104,7 +105,7 @@ pub async fn remote_write(
         .with_label_values(&[db.as_str()])
         .start_timer();
 
-    let request = decode_remote_write_request_to_row_inserts(body).await?;
+    let (request, samples) = decode_remote_write_request_to_row_inserts(body).await?;
 
     if let Some(physical_table) = params.physical_table {
         let mut new_query_ctx = query_ctx.as_ref().clone();
@@ -112,7 +113,8 @@ pub async fn remote_write(
         query_ctx = Arc::new(new_query_ctx);
     }
 
-    let output = handler.write_fast(request, query_ctx, true).await?;
+    let output = handler.write(request, query_ctx, true).await?;
+    crate::metrics::PROM_STORE_REMOTE_WRITE_SAMPLES.inc_by(samples as u64);
     Ok((
         StatusCode::NO_CONTENT,
         write_cost_header_map(output.meta.cost),
@@ -159,7 +161,9 @@ pub async fn remote_read(
     handler.read(request, query_ctx).await
 }
 
-async fn decode_remote_write_request_to_row_inserts(body: Body) -> Result<RowInsertRequests> {
+async fn decode_remote_write_request_to_row_inserts(
+    body: Body,
+) -> Result<(RowInsertRequests, usize)> {
     let _timer = crate::metrics::METRIC_HTTP_PROM_STORE_DECODE_ELAPSED.start_timer();
     let body = hyper::body::to_bytes(body)
         .await
@@ -171,24 +175,22 @@ async fn decode_remote_write_request_to_row_inserts(body: Body) -> Result<RowIns
     request
         .merge(buf)
         .context(error::DecodePromRemoteRequestSnafu)?;
-    let (requests, samples) = request.as_row_insert_requests();
-    crate::metrics::METRIC_HTTP_PROM_STORE_DECODE_NUM_SERIES.observe(samples as f64);
-    Ok(requests)
+    Ok(request.as_row_insert_requests())
 }
 
-async fn decode_remote_write_request(body: Body) -> Result<WriteRequest> {
+async fn decode_remote_write_request(body: Body) -> Result<(RowInsertRequests, usize)> {
     let _timer = crate::metrics::METRIC_HTTP_PROM_STORE_DECODE_ELAPSED.start_timer();
     let body = hyper::body::to_bytes(body)
         .await
         .context(error::HyperSnafu)?;
 
-    let buf = snappy_decompress(&body[..])?;
+    let buf = Bytes::from(snappy_decompress(&body[..])?);
 
-    let request = WriteRequest::decode(&buf[..]).context(error::DecodePromRemoteRequestSnafu)?;
-    crate::metrics::METRIC_HTTP_PROM_STORE_DECODE_NUM_SERIES
-        .observe(request.timeseries.len() as f64);
-
-    Ok(request)
+    let mut request = PromWriteRequest::default();
+    request
+        .merge(buf)
+        .context(error::DecodePromRemoteRequestSnafu)?;
+    Ok(request.as_row_insert_requests())
 }
 
 async fn decode_remote_read_request(body: Body) -> Result<ReadRequest> {

src/servers/src/metrics.rs

@@ -103,9 +103,10 @@ lazy_static! {
     /// Duration to convert prometheus write request to gRPC request.
     pub static ref METRIC_HTTP_PROM_STORE_CONVERT_ELAPSED: Histogram = METRIC_HTTP_PROM_STORE_CODEC_ELAPSED
         .with_label_values(&["convert"]);
-    pub static ref METRIC_HTTP_PROM_STORE_DECODE_NUM_SERIES: Histogram = register_histogram!(
-        "greptime_servers_http_prometheus_decode_num_series",
-        "servers http prometheus decode num series",
+        /// The samples count of Prometheus remote write.
+    pub static ref PROM_STORE_REMOTE_WRITE_SAMPLES: IntCounter = register_int_counter!(
+        "greptime_servers_prometheus_remote_write_samples",
+        "frontend prometheus remote write samples"
     )
     .unwrap();
     /// Http prometheus read duration per database.

src/servers/src/proto.rs

@@ -40,7 +40,10 @@ pub struct PromLabel {
 }
 
 impl Clear for PromLabel {
-    fn clear(&mut self) {}
+    fn clear(&mut self) {
+        self.name.clear();
+        self.value.clear();
+    }
 }
 
 impl PromLabel {

src/servers/src/query_handler.rs

@@ -28,7 +28,7 @@ pub mod sql;
 use std::collections::HashMap;
 use std::sync::Arc;
 
-use api::prom_store::remote::{ReadRequest, WriteRequest};
+use api::prom_store::remote::ReadRequest;
 use api::v1::RowInsertRequests;
 use async_trait::async_trait;
 use common_query::Output;
@@ -90,14 +90,6 @@ pub struct PromStoreResponse {
 pub trait PromStoreProtocolHandler {
     /// Handling prometheus remote write requests
     async fn write(
-        &self,
-        request: WriteRequest,
-        ctx: QueryContextRef,
-        with_metric_engine: bool,
-    ) -> Result<Output>;
-
-    /// Handling prometheus remote write requests
-    async fn write_fast(
         &self,
         request: RowInsertRequests,
         ctx: QueryContextRef,

src/servers/tests/http/prom_store_test.rs

@@ -58,16 +58,7 @@ impl GrpcQueryHandler for DummyInstance {
 
 #[async_trait]
 impl PromStoreProtocolHandler for DummyInstance {
-    async fn write(&self, request: WriteRequest, ctx: QueryContextRef, _: bool) -> Result<Output> {
-        let _ = self
-            .tx
-            .send((ctx.current_schema().to_owned(), request.encode_to_vec()))
-            .await;
-
-        Ok(Output::new_with_affected_rows(0))
-    }
-
-    async fn write_fast(
+    async fn write(
         &self,
         _request: RowInsertRequests,
         _ctx: QueryContextRef,