Cache otel tracing status and tracer on package load

Author: shikokuchuo

DESCRIPTION

@@ -57,5 +57,3 @@ Config/testthat/start-first: resp-stream, req-perform
 Encoding: UTF-8
 Roxygen: list(markdown = TRUE)
 RoxygenNote: 7.3.2
-Remotes:
-    r-lib/otelsdk

R/otel.R

@@ -1,3 +1,7 @@
+otel_tracer_name <- "org.r-lib.httr2"
+otel_tracer <- NULL
+otel_is_tracing <- FALSE
+
 # Attaches an Open Telemetry span that abides by the semantic conventions for
 # HTTP clients to the request, including the associated W3C trace context
 # headers.
@@ -6,11 +10,11 @@
 req_with_span <- function(
   req,
   resend_count = 0,
-  tracer = get_tracer(),
+  tracer = otel_tracer,
   activation_scope = parent.frame(),
   activate = TRUE
 ) {
-  if (!is_tracing(tracer)) {
+  if (!tracer_enabled(tracer)) {
     cli::cli_abort(
       "Cannot create request span; tracing is not enabled",
       .internal = TRUE
@@ -93,22 +97,24 @@ req_record_span_status <- function(req, resp = NULL) {
   }
 }
 
-get_tracer <- function() {
-  if (!is.null(the$tracer)) {
-    return(the$tracer)
-  }
-  if (!is_installed("otel")) {
-    return(NULL)
-  }
-  if (is_testing()) {
-    # Don't cache the tracer in unit tests. It interferes with tracer provider
-    # injection in otelsdk::with_otel_record().
-    return(otel::get_tracer("httr2"))
-  }
-  the$tracer <- otel::get_tracer("httr2")
-  the$tracer
+otel_cache_tracer <- function() {
+  requireNamespace("otel", quietly = TRUE) || return()
+  otel_tracer <<- otel::get_tracer(otel_tracer_name)
+  otel_is_tracing <<- tracer_enabled(otel_tracer)
+}
+
+tracer_enabled <- function(tracer) {
+  .subset2(tracer, "is_enabled")()
 }
 
-is_tracing <- function(tracer = get_tracer()) {
-  !is.null(tracer) && tracer$is_enabled()
+otel_refresh_tracer <- function(pkgname) {
+  requireNamespace("otel", quietly = TRUE) || return()
+  ns <- getNamespace(pkgname)
+  do.call(unlockBinding, list("otel_is_tracing", ns)) # do.call for R CMD Check
+  do.call(unlockBinding, list("otel_tracer", ns))
+  otel_tracer <- otel::get_tracer()
+  ns[["otel_is_tracing"]] <- tracer_enabled(otel_tracer)
+  ns[["otel_tracer"]] <- otel_tracer
+  lockBinding("otel_is_tracing", ns)
+  lockBinding("otel_tracer", ns)
 }

R/pooled-request.R

@@ -66,7 +66,7 @@ PooledRequest <- R6Class(
 
       private$req_prep <- req_prepare(req)
       private$handle <- req_handle(private$req_prep)
-      if (is_tracing()) {
+      if (otel_is_tracing) {
         # Note: we need to do this before we call handle_preflight() so that
         # request signing works correctly with the added headers.
         #

R/req-perform-connection.R

@@ -151,7 +151,7 @@ req_perform_connection1 <- function(
   the$last_request <- req
   the$last_response <- NULL
   signal(class = "httr2_perform_connection")
-  if (is_tracing()) {
+  if (otel_is_tracing) {
     # Note: we need to do this before we call handle_preflight() so that request
     # signing works correctly with the added headers.
     req_prep <- req_with_span(req_prep, resend_count = resend_count)

R/req-perform.R

@@ -190,7 +190,7 @@ req_perform1 <- function(
   the$last_request <- req
   the$last_response <- NULL
   signal(class = "httr2_perform")
-  if (is_tracing()) {
+  if (otel_is_tracing) {
     # Note: we need to do this before we call handle_preflight() so that request
     # signing works correctly with the added headers.
     req_prep <- req_with_span(req_prep, resend_count = resend_count)

R/zzz.R

@@ -1,3 +1,4 @@
 .onLoad <- function(...) {
+  otel_cache_tracer()
   cache_disk_prune()
 }

tests/testthat/test-req-perform-connection.R

@@ -117,6 +117,7 @@ test_that("tracing works as expected", {
   skip_if_not_installed("otelsdk")
 
   spans <- otelsdk::with_otel_record({
+    otel_refresh_tracer("httr2")
     # A request with no URL (which shouldn't create a span).
     try(req_perform_connection(request("")), silent = TRUE)
 
@@ -152,6 +153,9 @@ test_that("tracing works as expected", {
       try(silent = TRUE)
   })[["traces"]]
 
+  # reset tracer after tests
+  otel_refresh_tracer("httr2")
+
   expect_length(spans, 7L)
 
   # Validate the span for regular requests.

tests/testthat/test-req-perform-parallel.R

@@ -341,6 +341,7 @@ test_that("tracing works as expected", {
   skip_if_not_installed("otelsdk")
 
   spans <- otelsdk::with_otel_record({
+    otel_refresh_tracer("httr2")
     # A request with no URL (which shouldn't create a span).
     try(req_perform_parallel(list(request(""))), silent = TRUE)
 
@@ -373,6 +374,9 @@ test_that("tracing works as expected", {
     )
   })[["traces"]]
 
+  # reset tracer after tests
+  otel_refresh_tracer("httr2")
+
   expect_length(spans, 6L)
 
   # And for requests with HTTP errors.

tests/testthat/test-req-perform.R

@@ -226,6 +226,7 @@ test_that("tracing works as expected", {
   skip_if_not_installed("otelsdk")
 
   spans <- otelsdk::with_otel_record({
+    otel_refresh_tracer("httr2")
     # A request with no URL (which shouldn't create a span).
     try(req_perform(request("")), silent = TRUE)
 
@@ -260,6 +261,9 @@ test_that("tracing works as expected", {
       try(silent = TRUE)
   })[["traces"]]
 
+  # reset tracer after tests
+  otel_refresh_tracer("httr2")
+
   expect_length(spans, 7L)
 
   # Validate the span for regular requests.

tests/testthat/test-req-promise.R

@@ -176,6 +176,7 @@ test_that("tracing works as expected", {
   skip_if_not_installed("otelsdk")
 
   spans <- otelsdk::with_otel_record({
+    otel_refresh_tracer("httr2")
     # A request with no URL (which shouldn't create a span).
     try(req_perform_promise(request("")), silent = TRUE)
 
@@ -211,6 +212,8 @@ test_that("tracing works as expected", {
       "traceparent" %in% names(resp_body_json(resp)[["headers"]])
     )
   })[["traces"]]
+  # reset tracer after tests
+  otel_refresh_tracer("httr2")
 
   expect_length(spans, 5L)