1 files changed, 142 insertions, 0 deletions
diff --git a/devtools/client/debugger/src/actions/breakpoints/syncBreakpoint.js b/devtools/client/debugger/src/actions/breakpoints/syncBreakpoint.js
new file mode 100644
index 0000000000..495fbdd340
--- /dev/null
+++ b/devtools/client/debugger/src/actions/breakpoints/syncBreakpoint.js
@@ -0,0 +1,142 @@
+/* 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 { setBreakpointPositions } from "./breakpointPositions";
+import {
+  assertPendingBreakpoint,
+  findPosition,
+  makeBreakpointLocation,
+} from "../../utils/breakpoint";
+
+import { comparePosition, createLocation } from "../../utils/location";
+
+import {
+  originalToGeneratedId,
+  isOriginalId,
+} from "devtools/client/shared/source-map-loader/index";
+import { getSource } from "../../selectors";
+import { addBreakpoint, removeBreakpointAtGeneratedLocation } from ".";
+
+async function findBreakpointPosition(cx, { getState, dispatch }, location) {
+  const { sourceId, line } = location;
+  const positions = await dispatch(
+    setBreakpointPositions({ cx, sourceId, line })
+  );
+
+  const position = findPosition(positions, location);
+  return position;
+}
+
+// Breakpoint syncing occurs when a source is found that matches either the
+// original or generated URL of a pending breakpoint. A new breakpoint is
+// constructed that might have a different original and/or generated location,
+// if the original source has changed since the pending breakpoint was created.
+// There are a couple subtle aspects to syncing:
+//
+// - We handle both the original and generated source because there is no
+//   guarantee that seeing the generated source means we will also see the
+//   original source. When connecting, a breakpoint will be installed in the
+//   client for the generated location in the pending breakpoint, and we need
+//   to make sure that either a breakpoint is added to the reducer or that this
+//   client breakpoint is deleted.
+//
+// - If we see both the original and generated sources and the source mapping
+//   has changed, we need to make sure that only a single breakpoint is added
+//   to the reducer for the new location corresponding to the original location
+//   in the pending breakpoint.
+export function syncBreakpoint(cx, sourceId, pendingBreakpoint) {
+  return async thunkArgs => {
+    const { getState, client, dispatch } = thunkArgs;
+    assertPendingBreakpoint(pendingBreakpoint);
+
+    const source = getSource(getState(), sourceId);
+
+    const generatedSourceId = isOriginalId(sourceId)
+      ? originalToGeneratedId(sourceId)
+      : sourceId;
+
+    const generatedSource = getSource(getState(), generatedSourceId);
+
+    if (!source || !generatedSource) {
+      return null;
+    }
+
+    const { location, generatedLocation } = pendingBreakpoint;
+    const sourceGeneratedLocation = createLocation({
+      ...generatedLocation,
+      sourceId: generatedSourceId,
+    });
+
+    if (
+      source == generatedSource &&
+      location.sourceUrl != generatedLocation.sourceUrl
+    ) {
+      // We are handling the generated source and the pending breakpoint has a
+      // source mapping. Supply a cancellation callback that will abort the
+      // breakpoint if the original source was synced to a different location,
+      // in which case the client breakpoint has been removed.
+      const breakpointLocation = makeBreakpointLocation(
+        getState(),
+        sourceGeneratedLocation
+      );
+      return dispatch(
+        addBreakpoint(
+          cx,
+          sourceGeneratedLocation,
+          pendingBreakpoint.options,
+          pendingBreakpoint.disabled,
+          () => !client.hasBreakpoint(breakpointLocation)
+        )
+      );
+    }
+
+    const originalLocation = createLocation({
+      ...location,
+      sourceId,
+    });
+
+    const newPosition = await findBreakpointPosition(
+      cx,
+      thunkArgs,
+      originalLocation
+    );
+
+    const newGeneratedLocation = newPosition?.generatedLocation;
+    if (!newGeneratedLocation) {
+      // We couldn't find a new mapping for the breakpoint. If there is a source
+      // mapping, remove any breakpoints for the generated location, as if the
+      // breakpoint moved. If the old generated location still maps to an
+      // original location then we don't want to add a breakpoint for it.
+      if (location.sourceUrl != generatedLocation.sourceUrl) {
+        dispatch(
+          removeBreakpointAtGeneratedLocation(cx, sourceGeneratedLocation)
+        );
+      }
+      return null;
+    }
+
+    const isSameLocation = comparePosition(
+      generatedLocation,
+      newGeneratedLocation
+    );
+
+    // If the new generated location has changed from that in the pending
+    // breakpoint, remove any breakpoint associated with the old generated
+    // location.
+    if (!isSameLocation) {
+      dispatch(
+        removeBreakpointAtGeneratedLocation(cx, sourceGeneratedLocation)
+      );
+    }
+
+    return dispatch(
+      addBreakpoint(
+        cx,
+        newGeneratedLocation,
+        pendingBreakpoint.options,
+        pendingBreakpoint.disabled
+      )
+    );
+  };
+}