perf(profiling): speed up stack walking by using function run_time_cache

.gitlab-ci.yml

@@ -40,8 +40,9 @@ build:
 deploy_to_reliability_env:
   stage: deploy
   rules:
-    - if: '$CI_PIPELINE_SOURCE != "schedule"'
-      when: always
+    - if: '$FORCE_TRIGGER == "true"'
+    - if: '$CI_PIPELINE_SOURCE == "schedule"'
+      when: never
   trigger:
     project: DataDog/apm-reliability/datadog-reliability-env
     branch: $DOWNSTREAM_REL_BRANCH

profiling/Cargo.toml

@@ -11,21 +11,24 @@ crate-type = ["cdylib"]
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+ahash = { version = "0.8" }
 anyhow = { version = "1.0" }
+bumpalo = { version = "3.12", features = ["collections"] }
 cfg-if = { version = "1.0" }
-crossbeam-channel = { version = "0.5", default-features = false, features = ["std"] }
 cpu-time = { version = "1.0" }
+crossbeam-channel = { version = "0.5", default-features = false, features = ["std"] }
 datadog-profiling = { git = "https://github.com/DataDog/libdatadog", tag = "v2.0.0" }
-env_logger = { version = "0.9.3" }
+env_logger = { version = "0.10" }
 indexmap = { version = "1.8" }
 lazy_static = { version = "1.4" }
 libc = "0.2"
 # TRACE set to max to support runtime configuration.
 log = { version = "0.4", features = ["max_level_trace", "release_max_level_trace"]}
 once_cell = { version = "1.12" }
-uuid = { version = "1.0", features = ["v4"] }
 rand = { version = "0.8.5" }
 rand_distr = { version = "0.4.3" }
+self_cell = { version = "0.10" }
+uuid = { version = "1.0", features = ["v4"] }
 
 [features]
 default = ["allocation_profiling"]

profiling/src/bindings/mod.rs

@@ -268,6 +268,16 @@ extern "C" {
     /// strings will be converted into a string view to a static empty string
     /// (single byte of null, len of 0).
     pub fn ddog_php_prof_zend_string_view(zstr: Option<&mut zend_string>) -> zai_string_view;
+
+    /// Registers the run_time_cache slot with the engine. Must be done in
+    /// module init or extension startup.
+    pub fn ddog_php_prof_function_run_time_cache_init(module_name: *const c_char);
+
+    /// Gets the address of a function's run_time_cache slot. May return None
+    /// if it detects incomplete initialization, which is always a bug but
+    /// none-the-less has been seen in the wild. It may also return None if
+    /// the run_time_cache is not available on this function type.
+    pub fn ddog_php_prof_function_run_time_cache(func: &zend_function) -> Option<&mut [usize; 2]>;
 }
 
 #[cfg(php_preload)]
@@ -498,3 +508,21 @@ pub struct ZaiConfigMemoizedEntry {
         ) -> c_int,
     >,
 }
+
+#[cfg(test)]
+mod tests {
+
+    // If this fails, then ddog_php_prof_function_run_time_cache needs to be
+    // adjusted accordingly.
+    #[test]
+    fn test_sizeof_fixed_size_slice_is_same_as_pointer() {
+        assert_eq!(
+            std::mem::size_of::<&[usize; 2]>(),
+            std::mem::size_of::<*mut usize>()
+        );
+        assert_eq!(
+            std::mem::align_of::<&[usize; 2]>(),
+            std::mem::align_of::<*mut usize>()
+        );
+    }
+}