Implement asynchronous scope identifiers.

Without entering an asynchronous scope, logs are the same before.  When
entering an asynchronous scope (either thread-based of
scheduler/task-based), all log lines within an asynchronous scope
contain its ID.

Currently this is only used in GNU Taler, for debugging requests across
multiple services.  This allows us to get all log lines pertaining to a
particular request for a user or another service.

1 files changed, 76 insertions, 13 deletions

diff --git a/src/curl/curl.c b/src/curl/curl.c
index e13c1478f..871401c60 100644
--- a/src/curl/curl.c
+++ b/src/curl/curl.c
@@ -105,6 +105,18 @@ struct GNUNET_CURL_Job
    * Buffer for response received from CURL.
    */
   struct GNUNET_CURL_DownloadBuffer db;
+
+  /**
+   * Headers used for this job, the list needs to be freed
+   * after the job has finished.
+   */
+  struct curl_slist *job_headers;
+
+  /**
+   * Header for the async scope id or NULL.
+   */
+  char *aid_header;
+
 };
 
 
@@ -134,10 +146,15 @@ struct GNUNET_CURL_Context
   struct GNUNET_CURL_Job *jobs_tail;
 
   /**
-   * HTTP header "application/json", created once and used
-   * for all requests that need it.
+   * Headers common for all requests in the context.
+   */
+  struct curl_slist *common_headers;
+
+  /**
+   * If non-NULL, the async scope ID is sent in a request
+   * header of this name.
    */
-  struct curl_slist *json_header;
+  const char *async_scope_id_header;
 
   /**
    * Function we need to call whenever the event loop's
@@ -149,6 +166,7 @@ struct GNUNET_CURL_Context
    * Closure for @e cb.
    */
   void *cb_cls;
+
 };
 
 
@@ -189,14 +207,24 @@ GNUNET_CURL_init (GNUNET_CURL_RescheduleCallback cb, void *cb_cls)
   ctx->cb_cls = cb_cls;
   ctx->multi = multi;
   ctx->share = share;
-  GNUNET_assert (
-    NULL != (ctx->json_header =
-               curl_slist_append (NULL, "Content-Type: application/json")));
   return ctx;
 }
 
 
 /**
+ * Enable sending the async scope ID as a header.
+ *
+ * @param ctx the context to enable this for
+ * @param header_name name of the header to send.
+ */
+void
+GNUNET_CURL_enable_async_scope_header (struct GNUNET_CURL_Context *ctx, const char *header_name)
+{
+  ctx->async_scope_id_header = header_name;
+}
+
+
+/**
  * Callback used when downloading the reply to an HTTP request.
  * Just appends all of the data to the `buf` in the
  * `struct DownloadBuffer` for further processing. The size of
@@ -259,16 +287,49 @@ GNUNET_CURL_job_add (struct GNUNET_CURL_Context *ctx,
                      void *jcc_cls)
 {
   struct GNUNET_CURL_Job *job;
+  struct curl_slist *all_headers = NULL;
+  char *aid_header = NULL;
 
   if (GNUNET_YES == add_json)
-    if (CURLE_OK != curl_easy_setopt (eh, CURLOPT_HTTPHEADER, ctx->json_header))
+  {
+    GNUNET_assert (
+      NULL != (all_headers =
+                 curl_slist_append (NULL, "Content-Type: application/json")));
+  }
+
+  for (struct curl_slist *curr = ctx->common_headers;
+       curr != NULL;
+       curr = curr->next)
+  {
+    GNUNET_assert (
+      NULL != (all_headers =
+                 curl_slist_append (all_headers, "Content-Type: application/json")));
+  }
+
+  if (NULL != ctx->async_scope_id_header)
+  {
+    struct GNUNET_AsyncScopeSave scope;
+
+    GNUNET_async_scope_get (&scope);
+    if (GNUNET_YES == scope.have_scope)
     {
-      GNUNET_break (0);
-      curl_easy_cleanup (eh);
-      return NULL;
+      aid_header = GNUNET_STRINGS_data_to_string_alloc (&scope.scope_id,
+                                                        sizeof (struct GNUNET_AsyncScopeId));
+      GNUNET_assert (NULL != curl_slist_append(all_headers, aid_header));
     }
+  }
+
+  if (CURLE_OK != curl_easy_setopt (eh, CURLOPT_HTTPHEADER, all_headers))
+  {
+    GNUNET_break (0);
+    curl_easy_cleanup (eh);
+    return NULL;
+  }
 
   job = GNUNET_new (struct GNUNET_CURL_Job);
+  job->job_headers = all_headers;
+  job->aid_header = aid_header;
+
   if ((CURLE_OK != curl_easy_setopt (eh, CURLOPT_PRIVATE, job)) ||
       (CURLE_OK !=
        curl_easy_setopt (eh, CURLOPT_WRITEFUNCTION, &download_cb)) ||
@@ -308,6 +369,8 @@ GNUNET_CURL_job_cancel (struct GNUNET_CURL_Job *job)
                 curl_multi_remove_handle (ctx->multi, job->easy_handle));
   curl_easy_cleanup (job->easy_handle);
   GNUNET_free_non_null (job->db.buf);
+  GNUNET_free_non_null (job->aid_header);
+  curl_slist_free_all (job->job_headers);
   GNUNET_free (job);
 }
 
@@ -401,8 +464,8 @@ download_get_result (struct GNUNET_CURL_DownloadBuffer *db,
 int
 GNUNET_CURL_append_header (struct GNUNET_CURL_Context *ctx, const char *header)
 {
-  ctx->json_header = curl_slist_append (ctx->json_header, header);
-  if (NULL == ctx->json_header)
+  ctx->common_headers = curl_slist_append (ctx->common_headers, header);
+  if (NULL == ctx->common_headers)
     return GNUNET_SYSERR;
 
   return GNUNET_OK;
@@ -599,7 +662,7 @@ GNUNET_CURL_fini (struct GNUNET_CURL_Context *ctx)
   GNUNET_assert (NULL == ctx->jobs_head);
   curl_share_cleanup (ctx->share);
   curl_multi_cleanup (ctx->multi);
-  curl_slist_free_all (ctx->json_header);
+  curl_slist_free_all (ctx->common_headers);
   GNUNET_free (ctx);
 }