fix: more work to prevent queries from running when there's in-progre…

…ss node processing (#8859)

* More work to prevent queries from running when there's in-progress node processing

* Remove unused code

* Turns out having query running pause on CREATE_NODE is all that's needed

* Make state machine local to each instance of the plugin

packages/gatsby-source-filesystem/src/gatsby-node.js

@@ -44,27 +44,6 @@ const createFSMachine = () =>
           },
         },
       },
-      PROCESSING: {
-        initial: `BOOTSTRAPPING`,
-        states: {
-          BOOTSTRAPPING: {
-            on: {
-              BOOTSTRAP_FINISHED: `IDLE`,
-            },
-          },
-          IDLE: {
-            on: {
-              EMIT_FS_EVENT: `PROCESSING`,
-            },
-          },
-          PROCESSING: {
-            on: {
-              QUERY_QUEUE_DRAINED: `IDLE`,
-              TOUCH_NODE: `IDLE`,
-            },
-          },
-        },
-      },
     },
   })
 
@@ -95,7 +74,6 @@ See docs here - https://www.gatsbyjs.org/packages/gatsby-source-filesystem/
 
   const fsMachine = createFSMachine()
   let currentState = fsMachine.initialState
-  let fileNodeQueue = new Map()
 
   // Once bootstrap is finished, we only let one File node update go through
   // the system at a time.
@@ -105,26 +83,6 @@ See docs here - https://www.gatsbyjs.org/packages/gatsby-source-filesystem/
       `BOOTSTRAP_FINISHED`
     )
   })
-  emitter.on(`TOUCH_NODE`, () => {
-    // If we create a node which is the same as the previous version, createNode
-    // returns TOUCH_NODE and then nothing else happens so we listen to that
-    // to return the state back to IDLE.
-    currentState = fsMachine.transition(currentState.value, `TOUCH_NODE`)
-  })
-
-  emitter.on(`QUERY_QUEUE_DRAINED`, () => {
-    currentState = fsMachine.transition(
-      currentState.value,
-      `QUERY_QUEUE_DRAINED`
-    )
-    // If we have any updates queued, run one of them now.
-    if (fileNodeQueue.size > 0) {
-      const toProcess = fileNodeQueue.get(Array.from(fileNodeQueue.keys())[0])
-      fileNodeQueue.delete(toProcess.id)
-      currentState = fsMachine.transition(currentState.value, `EMIT_FS_EVENT`)
-      createNode(toProcess)
-    }
-  })
 
   const watcher = chokidar.watch(pluginOptions.path, {
     ignored: [
@@ -147,13 +105,7 @@ See docs here - https://www.gatsbyjs.org/packages/gatsby-source-filesystem/
       createNodeId,
       pluginOptions
     ).then(fileNode => {
-      if (currentState.value.PROCESSING === `PROCESSING`) {
-        fileNodeQueue.set(fileNode.id, fileNode)
-      } else {
-        currentState = fsMachine.transition(currentState.value, `EMIT_FS_EVENT`)
-        createNode(fileNode)
-      }
-
+      createNode(fileNode)
       return null
     })
     return fileNodePromise
@@ -201,7 +153,6 @@ See docs here - https://www.gatsbyjs.org/packages/gatsby-source-filesystem/
     // It's possible the file node was never created as sometimes tools will
     // write and then immediately delete temporary files to the file system.
     if (node) {
-      currentState = fsMachine.transition(currentState.value, `EMIT_FS_EVENT`)
       deleteNode({ node })
     }
   })

packages/gatsby/src/internal-plugins/query-runner/query-queue.js

@@ -61,8 +61,22 @@ const queue = new Queue((plObj, callback) => {
     )
 }, queueOptions)
 
+// Pause running queries when new nodes are added (processing starts).
+emitter.on(`CREATE_NODE`, () => {
+  queue.pause()
+})
+
+// Resume running queries as soon as the api queue is empty.
+emitter.on(`API_RUNNING_QUEUE_EMPTY`, () => {
+  queue.resume()
+})
+
 queue.on(`drain`, () => {
   emitter.emit(`QUERY_QUEUE_DRAINED`)
 })
 
+queue.on(`task_queued`, () => {
+  emitter.emit(`QUERY_ENQUEUED`)
+})
+
 module.exports = queue