feat: Add HTTP API for cpu profiling

Cargo.toml

@@ -17,6 +17,7 @@ members = [
     "src/common/meta",
     "src/common/procedure",
     "src/common/procedure-test",
+    "src/common/pprof",
     "src/common/query",
     "src/common/recordbatch",
     "src/common/runtime",

src/common/mem-prof/src/error.rs

@@ -23,7 +23,7 @@ pub type Result<T> = std::result::Result<T, Error>;
 #[derive(Debug, Snafu)]
 #[snafu(visibility(pub))]
 pub enum Error {
-    #[snafu(display("Failed to read OPT_PROF"))]
+    #[snafu(display("Failed to read OPT_PROF, source: {}", source))]
     ReadOptProf { source: tikv_jemalloc_ctl::Error },
 
     #[snafu(display("Memory profiling is not enabled"))]
@@ -32,13 +32,17 @@ pub enum Error {
     #[snafu(display("Failed to build temp file from given path: {:?}", path))]
     BuildTempPath { path: PathBuf, location: Location },
 
-    #[snafu(display("Failed to open temp file: {}", path))]
+    #[snafu(display("Failed to open temp file: {}, source: {}", path, source))]
     OpenTempFile {
         path: String,
         source: std::io::Error,
     },
 
-    #[snafu(display("Failed to dump profiling data to temp file: {:?}", path))]
+    #[snafu(display(
+        "Failed to dump profiling data to temp file: {:?}, source: {}",
+        path,
+        source
+    ))]
     DumpProfileData {
         path: PathBuf,
         source: tikv_jemalloc_ctl::Error,

src/common/pprof/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "common-pprof"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[dependencies]
+common-error = { path = "../error" }
+pprof = { version = "0.11", features = [
+    "flamegraph",
+    "prost-codec",
+    "protobuf",
+] }
+prost.workspace = true
+snafu.workspace = true
+tokio.workspace = true

src/common/pprof/README.md

@@ -0,0 +1,28 @@
+# Profiling CPU
+
+## Build GreptimeDB with `pprof` feature
+
+```bash
+cargo build --features=pprof
+```
+
+## HTTP API
+Sample at 99 Hertz, for 5 seconds, output report in [protobuf format](https://github.com/google/pprof/blob/master/proto/profile.proto).
+```bash
+curl -s '0:4000/v1/prof/cpu' > /tmp/pprof.out
+```
+
+Then you can use `pprof` command with the protobuf file.
+```bash
+go tool pprof -top /tmp/pprof.out
+```
+
+Sample at 99 Hertz, for 60 seconds, output report in flamegraph format.
+```bash
+curl -s '0:4000/v1/prof/cpu?seconds=60&output=flamegraph' > /tmp/pprof.svg
+```
+
+Sample at 49 Hertz, for 10 seconds, output report in text format.
+```bash
+curl -s '0:4000/v1/prof/cpu?seconds=10&frequency=49&output=text' > /tmp/pprof.txt
+```