feat: add HTTP endpoint to control prof.gdump feature (#6999)

* feat/gdump:
 ### Add Support for Jemalloc Gdump Flag

 - **`jemalloc.rs`**: Introduced `PROF_GDUMP` constant and added functions `set_gdump_active` and `is_gdump_active` to manage the gdump flag.
 - **`error.rs`**: Added error handling for reading and updating the jemalloc gdump flag with `ReadGdump` and `UpdateGdump` errors.
 - **`lib.rs`**: Exposed `is_gdump_active` and `set_gdump_active` functions for non-Windows platforms.
 - **`http.rs`**: Added HTTP routes for checking and toggling the jemalloc gdump flag status.
 - **`mem_prof.rs`**: Implemented handlers `gdump_toggle_handler` and `gdump_status_handler` for managing gdump flag via HTTP requests.

Signed-off-by: Lei, HUANG <mrsatangel@gmail.com>

* Update docs/how-to/how-to-profile-memory.md

Co-authored-by: shuiyisong <113876041+shuiyisong@users.noreply.github.com>

* fix: typo in docs

Signed-off-by: Lei, HUANG <mrsatangel@gmail.com>

---------

Signed-off-by: Lei, HUANG <mrsatangel@gmail.com>
Co-authored-by: shuiyisong <113876041+shuiyisong@users.noreply.github.com>

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

@@ -32,6 +32,7 @@ use crate::error::{FlamegraphSnafu, ParseJeHeapSnafu, Result};
 const PROF_DUMP: &[u8] = b"prof.dump\0";
 const OPT_PROF: &[u8] = b"opt.prof\0";
 const PROF_ACTIVE: &[u8] = b"prof.active\0";
+const PROF_GDUMP: &[u8] = b"prof.gdump\0";
 
 pub async fn dump_profile() -> Result<Vec<u8>> {
     ensure!(is_prof_enabled()?, ProfilingNotEnabledSnafu);
@@ -119,3 +120,16 @@ fn is_prof_enabled() -> Result<bool> {
     // safety: OPT_PROF variable, if present, is always a boolean value.
     Ok(unsafe { tikv_jemalloc_ctl::raw::read::<bool>(OPT_PROF).context(ReadOptProfSnafu)? })
 }
+
+pub fn set_gdump_active(active: bool) -> Result<()> {
+    ensure!(is_prof_enabled()?, ProfilingNotEnabledSnafu);
+    unsafe {
+        tikv_jemalloc_ctl::raw::update(PROF_GDUMP, active).context(error::UpdateGdumpSnafu)?;
+    }
+    Ok(())
+}
+
+pub fn is_gdump_active() -> Result<bool> {
+    // safety: PROF_GDUMP, if present, is a boolean value.
+    unsafe { Ok(tikv_jemalloc_ctl::raw::read::<bool>(PROF_GDUMP).context(error::ReadGdumpSnafu)?) }
+}

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

@@ -71,6 +71,18 @@ pub enum Error {
         #[snafu(source)]
         error: tikv_jemalloc_ctl::Error,
     },
+
+    #[snafu(display("Failed to read jemalloc gdump flag"))]
+    ReadGdump {
+        #[snafu(source)]
+        error: tikv_jemalloc_ctl::Error,
+    },
+
+    #[snafu(display("Failed to update jemalloc gdump flag"))]
+    UpdateGdump {
+        #[snafu(source)]
+        error: tikv_jemalloc_ctl::Error,
+    },
 }
 
 impl ErrorExt for Error {
@@ -84,6 +96,8 @@ impl ErrorExt for Error {
             Error::ActivateProf { .. } => StatusCode::Internal,
             Error::DeactivateProf { .. } => StatusCode::Internal,
             Error::ReadProfActive { .. } => StatusCode::Internal,
+            Error::ReadGdump { .. } => StatusCode::Internal,
+            Error::UpdateGdump { .. } => StatusCode::Internal,
         }
     }
 

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

@@ -19,7 +19,7 @@ mod jemalloc;
 #[cfg(not(windows))]
 pub use jemalloc::{
     activate_heap_profile, deactivate_heap_profile, dump_flamegraph, dump_pprof, dump_profile,
-    is_heap_profile_active,
+    is_gdump_active, is_heap_profile_active, set_gdump_active,
 };
 
 #[cfg(windows)]
@@ -51,3 +51,13 @@ pub fn deactivate_heap_profile() -> error::Result<()> {
 pub fn is_heap_profile_active() -> error::Result<bool> {
     error::ProfilingNotSupportedSnafu.fail()
 }
+
+#[cfg(windows)]
+pub fn is_gdump_active() -> error::Result<bool> {
+    error::ProfilingNotSupportedSnafu.fail()
+}
+
+#[cfg(windows)]
+pub fn set_gdump_active(_: bool) -> error::Result<()> {
+    error::ProfilingNotSupportedSnafu.fail()
+}