1 files changed, 89 insertions, 0 deletions
diff --git a/dom/base/usecounters.py b/dom/base/usecounters.py
new file mode 100644
index 0000000000..7e2c7148ec
--- /dev/null
+++ b/dom/base/usecounters.py
@@ -0,0 +1,89 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import collections
+import re
+
+
+def read_conf(conf_filename):
+    # Can't read/write from a single StringIO, so make a new one for reading.
+    stream = open(conf_filename, "r")
+
+    def parse_counters(stream):
+        for line_num, line in enumerate(stream):
+            line = line.rstrip("\n")
+            if not line or line.startswith("//"):
+                # empty line or comment
+                continue
+            m = re.match(r"method ([A-Za-z0-9]+)\.([A-Za-z0-9]+)$", line)
+            if m:
+                interface_name, method_name = m.groups()
+                yield {
+                    "type": "method",
+                    "interface_name": interface_name,
+                    "method_name": method_name,
+                }
+                continue
+            m = re.match(r"attribute ([A-Za-z0-9]+)\.([A-Za-z0-9]+)$", line)
+            if m:
+                interface_name, attribute_name = m.groups()
+                yield {
+                    "type": "attribute",
+                    "interface_name": interface_name,
+                    "attribute_name": attribute_name,
+                }
+                continue
+            m = re.match(r"custom ([A-Za-z0-9_]+) (.*)$", line)
+            if m:
+                name, desc = m.groups()
+                yield {"type": "custom", "name": name, "desc": desc}
+                continue
+            raise ValueError(
+                "error parsing %s at line %d" % (conf_filename, line_num + 1)
+            )
+
+    return parse_counters(stream)
+
+
+def generate_histograms(filename, is_for_worker=False):
+    # The mapping for use counters to telemetry histograms depends on the
+    # ordering of items in the dictionary.
+
+    # The ordering of the ending for workers depends on the WorkerType defined
+    # in WorkerPrivate.h.
+    endings = (
+        ["DEDICATED_WORKER", "SHARED_WORKER", "SERVICE_WORKER"]
+        if is_for_worker
+        else ["DOCUMENT", "PAGE"]
+    )
+
+    items = collections.OrderedDict()
+    for counter in read_conf(filename):
+
+        def append_counter(name, desc):
+            items[name] = {
+                "expires_in_version": "never",
+                "kind": "boolean",
+                "description": desc,
+            }
+
+        def append_counters(name, desc):
+            for ending in endings:
+                append_counter(
+                    "USE_COUNTER2_%s_%s" % (name, ending),
+                    "Whether a %s %s" % (ending.replace("_", " ").lower(), desc),
+                )
+
+        if counter["type"] == "method":
+            method = "%s.%s" % (counter["interface_name"], counter["method_name"])
+            append_counters(method.replace(".", "_").upper(), "called %s" % method)
+        elif counter["type"] == "attribute":
+            attr = "%s.%s" % (counter["interface_name"], counter["attribute_name"])
+            counter_name = attr.replace(".", "_").upper()
+            append_counters("%s_getter" % counter_name, "got %s" % attr)
+            append_counters("%s_setter" % counter_name, "set %s" % attr)
+        elif counter["type"] == "custom":
+            append_counters(counter["name"].upper(), counter["desc"])
+
+    return items