Revert "Revert "Channel Tracing Implementation; Part 1""

This reverts commit f2bea3725f8218777268decfd37c7b543f839d9f.

2 files changed, 56 insertions, 1 deletions

diff --git a/src/core/lib/json/json.cc b/src/core/lib/json/json.cc
index 2141db4c5b..816241bbf0 100644
--- a/src/core/lib/json/json.cc
+++ b/src/core/lib/json/json.cc
@@ -21,6 +21,7 @@
 #include <string.h>
 
 #include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
 
 #include "src/core/lib/json/json.h"
 
@@ -46,5 +47,40 @@ void grpc_json_destroy(grpc_json* json) {
     json->parent->child = json->next;
   }
 
+  if (json->owns_value) {
+    gpr_free((void*)json->value);
+  }
+
   gpr_free(json);
 }
+
+grpc_json* grpc_json_link_child(grpc_json* parent, grpc_json* child,
+                                grpc_json* sibling) {
+  // first child case.
+  if (parent->child == nullptr) {
+    GPR_ASSERT(sibling == nullptr);
+    parent->child = child;
+    return child;
+  }
+  if (sibling == nullptr) {
+    sibling = parent->child;
+  }
+  // always find the right most sibling.
+  while (sibling->next != nullptr) {
+    sibling = sibling->next;
+  }
+  sibling->next = child;
+  return child;
+}
+
+grpc_json* grpc_json_create_child(grpc_json* sibling, grpc_json* parent,
+                                  const char* key, const char* value,
+                                  grpc_json_type type, bool owns_value) {
+  grpc_json* child = grpc_json_create(type);
+  grpc_json_link_child(parent, child, sibling);
+  child->owns_value = owns_value;
+  child->parent = parent;
+  child->value = value;
+  child->key = key;
+  return child;
+}
diff --git a/src/core/lib/json/json.h b/src/core/lib/json/json.h
index 3a62ef9cfb..f93b43048b 100644
--- a/src/core/lib/json/json.h
+++ b/src/core/lib/json/json.h
@@ -21,6 +21,7 @@
 
 #include <grpc/support/port_platform.h>
 
+#include <stdbool.h>
 #include <stdlib.h>
 
 #include "src/core/lib/json/json_common.h"
@@ -37,6 +38,9 @@ typedef struct grpc_json {
   grpc_json_type type;
   const char* key;
   const char* value;
+
+  /* if set, destructor will free value */
+  bool owns_value;
 } grpc_json;
 
 /* The next two functions are going to parse the input string, and
@@ -67,9 +71,24 @@ char* grpc_json_dump_to_string(grpc_json* json, int indent);
 
 /* Use these to create or delete a grpc_json object.
  * Deletion is recursive. We will not attempt to free any of the strings
- * in any of the objects of that tree.
+ * in any of the objects of that tree, unless the boolean, owns_value,
+ * is true.
  */
 grpc_json* grpc_json_create(grpc_json_type type);
 void grpc_json_destroy(grpc_json* json);
 
+/* Links the child json object into the parent's json tree. If the parent
+ * already has children, then passing in the most recently added child as the
+ * sibling parameter is an optimization. For if sibling is NULL, this function
+ * will manually traverse the tree in order to find the right most sibling.
+ */
+grpc_json* grpc_json_link_child(grpc_json* parent, grpc_json* child,
+                                grpc_json* sibling);
+
+/* Creates a child json object into the parent's json tree then links it in
+ * as described above. */
+grpc_json* grpc_json_create_child(grpc_json* sibling, grpc_json* parent,
+                                  const char* key, const char* value,
+                                  grpc_json_type type, bool owns_value);
+
 #endif /* GRPC_CORE_LIB_JSON_JSON_H */