chore(migrate): instrument with some debug logging

packages/@sanity/migrate/package.json

@@ -68,6 +68,7 @@
     "@sanity/types": "^3.23.4",
     "@sanity/util": "3.26.1",
     "arrify": "^2.0.1",
+    "debug": "^4.3.4",
     "fast-fifo": "^1.3.2",
     "groq-js": "^1.4.1",
     "p-map": "^7.0.1"

packages/@sanity/migrate/src/debug.ts

@@ -0,0 +1,3 @@
+import createDebug from 'debug'
+
+export default createDebug('sanity:migrate')

packages/@sanity/migrate/src/fs-webstream/bufferThroughFile.ts

@@ -1,4 +1,7 @@
 import {FileHandle, open} from 'node:fs/promises'
+import baseDebug from '../debug'
+
+const debug = baseDebug.extend('bufferThroughFile')
 
 const CHUNK_SIZE = 1024
 
@@ -30,6 +33,7 @@ export function bufferThroughFile(
   let bufferDone = false
 
   signal?.addEventListener('abort', async () => {
+    debug('Aborting bufferThroughFile')
     await Promise.all([
       writeHandle && writeHandle.close(),
       readHandle && (await readHandle).close(),
@@ -69,6 +73,7 @@ export function bufferThroughFile(
         totalBytesRead,
       )
       if (bytesRead === 0 && !bufferDone && !signal?.aborted) {
+        debug('Not enough data in buffer file, waiting for more data to be written')
         // we're waiting for more data to be written to the buffer file, try again
         return tryReadFromBuffer(handle)
       }
@@ -80,17 +85,22 @@ export function bufferThroughFile(
   function init(): Promise<void> {
     if (!ready) {
       ready = (async () => {
+        debug('Initializing bufferThroughFile')
         writeHandle = await open(filename, 'w')
         // start pumping data from the source stream to the buffer file
         // note, don't await this, as it will block the ReadableStream.start() method
-        pump(source.getReader())
+        debug('Start buffering source stream to file')
+        pump(source.getReader()).then(() => {
+          debug('Buffering source stream to buffer file')
+        })
       })()
     }
     return ready
   }
 
   function getReadHandle(): Promise<FileHandle> {
     if (!readHandle) {
+      debug('Opening read handle on %s', filename)
       readHandle = open(filename, 'r')
     }
     return readHandle
@@ -104,6 +114,7 @@ export function bufferThroughFile(
     if (readerCount === 0 && readHandle) {
       const handle = readHandle
       readHandle = null
+      debug('Closing read handle on %s', filename)
       await (await handle).close()
     }
   }
@@ -116,6 +127,7 @@ export function bufferThroughFile(
         if (signal?.aborted) {
           throw new Error('Cannot create new buffered readers on aborted stream')
         }
+        debug('Reader started reading from file handle')
         onReaderStart()
         await init()
         await getReadHandle()
@@ -126,6 +138,7 @@ export function bufferThroughFile(
         }
         const {bytesRead, buffer} = await readChunk(await readHandle)
         if (bytesRead === 0 && bufferDone) {
+          debug('Reader done reading from file handle')
           await onReaderEnd()
           controller.close()
         } else {

packages/@sanity/migrate/src/fs-webstream/readFileAsWebStream.ts

@@ -1,5 +1,8 @@
 import type {FileHandle} from 'node:fs/promises'
 import {open} from 'node:fs/promises'
+import baseDebug from '../debug'
+
+const debug = baseDebug.extend('readFileAsWebStream')
 
 export function readFileAsWebStream(filename: string): ReadableStream<Uint8Array> {
   const CHUNK_SIZE = 1024
@@ -9,6 +12,7 @@ export function readFileAsWebStream(filename: string): ReadableStream<Uint8Array
 
   return new ReadableStream({
     async start() {
+      debug('Starting readable stream from', filename)
       fileHandle = await open(filename, 'r')
     },
     async pull(controller) {
@@ -17,6 +21,7 @@ export function readFileAsWebStream(filename: string): ReadableStream<Uint8Array
       const {bytesRead} = await fileHandle.read(buffer, 0, CHUNK_SIZE, position)
       if (bytesRead === 0) {
         await fileHandle.close()
+        debug('Closing readable stream from', filename)
         controller.close()
       } else {
         position += bytesRead
@@ -25,6 +30,7 @@ export function readFileAsWebStream(filename: string): ReadableStream<Uint8Array
     },
 
     cancel() {
+      debug('Cancelling readable stream from', filename)
       return fileHandle.close()
     },
   })