record io

README.md

@@ -130,6 +130,7 @@ there is cached result.
 
 Builtin IO functions are mocked to cache IO. Current list of builtin cached
 functions is:
+- `Date` constructor
 - `Math.random()`
 - `fetch`
 
@@ -148,7 +149,8 @@ Caching algorithm is:
   `write`
 
 - Arguments to IO-caching functions are expected to be deep equal to non-cached
-  call, for cache to be used
+  call, for cache to be used. Deep equality is implemented as comparing JSON
+  stringified arguments
 
 - If there is a call that is not cached, then cache is busted and entire
   execution is restarted

docs/examples/ethers/index.js

@@ -3,12 +3,29 @@ import {ethers} from 'https://unpkg.com/ethers/dist/ethers.esm.js'
 const URL = 'https://ethereum-goerli-rpc.allthatnode.com'
 
 const p = ethers.getDefaultProvider(URL)
+await p._networkPromise
 
 const latest = await p.getBlock()
+latest
+
 
 const txs = await Promise.all(latest.transactions.map(t => 
   p.getTransactionReceipt(t)
 ))
 
+
+
 const totalGas = txs.reduce((gas,tx) => 
   gas.add(tx.gasUsed), ethers.BigNumber.from(0))
+  
+  totalGas.add(25)
+  
+
+
+  
+  
+  
+
+  
+
+  

record_io/ethers.html

@@ -0,0 +1,261 @@
+<script>
+    let io_cache = null
+
+    let io_cache_is_recording = io_cache == null
+    if(io_cache == null) {
+      io_cache = {calls: [], resolution_order: []}
+    }
+    let io_cache_is_replay_aborted = false
+    let io_cache_index = 0
+
+    const io_patch = (obj, method, name, use_context = false) => {
+      if(obj == null || obj[method] == null) {
+        // Method is absent in current env, skip patching
+        return
+      }
+      const original = obj[method]
+      obj[method] = function(...args) {
+        console.log('patched method', name, {io_cache_is_replay_aborted, io_cache_is_recording})
+        // TODO guard that in find_call io methods are not called?
+        // if(searched_location != null) {
+        //   throw new Error('illegal state')
+        // }
+        if(io_cache_is_replay_aborted) {
+          // Try to finish fast
+          console.error('ABORT')
+          throw new Error('io recording aborted')
+        } else if(io_cache_is_recording) {
+          let ok, value, error
+          const has_new_target = new.target != null
+          try {
+            // TODO. Do we need it here? Only need for IO calls view. And also
+            // for expand_call and find_call, to not use cache on expand call
+            // and find_call
+            //set_record_call()
+            value = has_new_target 
+              ? new original(...args)
+              : original.apply(this, args)
+
+            console.log('value', value)
+
+            //const index = io_cache.calls.length
+            //if(value instanceof Promise) {
+            //  value.finally(() => {
+            //    console.log('resolved', index)
+            //    io_cache.resolution_order.push(index)
+            //  })
+            //} else {
+            //  io_cache.resolution_order.push(index)
+            //}
+
+            /* TODO remove
+            if(value instanceof Promise) {
+              const original_value = value
+              value = new Promise((resolve, reject) => {
+                // TODO fix setTimeout.original
+                globalThis.setTimeout.original(
+                  () => {
+                    original_value.then(resolve, reject)
+                  },
+                  10
+                )
+              })
+            }
+            */
+            // TODO
+            //if(value instanceof Promise) {
+            //  const make_cb = ok => value => {
+            //  // TODO resolve promises in the same order they were resolved on
+                // initial execution
+
+            //  }
+            //  // TODO should we use promise_then or patched promise.then?
+            //  promise_then.apply(value, make_cb(true), make_cb(false))
+            //}
+            ok = true
+            return value
+          } catch(e) {
+            error = e
+            ok = false
+            throw e
+          } finally {
+            io_cache.calls.push({
+              ok, 
+              value, 
+              error, 
+              args, 
+              name,
+              // To discern calls with and without 'new' keyword, primary for
+              // Date that can be called with and without new
+              has_new_target,
+              use_context,
+              context: use_context ? this : undefined,
+            })
+          }
+        } else {
+          const call = io_cache.calls[io_cache_index++]
+          /*
+          TODO remove
+          console.log(
+            call == null
+            , call.has_new_target != (new.target != null)
+            , call.use_context && (call.context != this)
+            , call.name != name
+            , JSON.stringify(call.args) != JSON.stringify(args)
+          )
+          */
+          if(
+            call == null
+            || call.has_new_target != (new.target != null)
+              // TODO test
+            || call.use_context && (call.context != this)
+            || call.name != name
+            || JSON.stringify(call.args) != JSON.stringify(args)
+          ){
+            console.log('discard cache', call)
+            io_cache_is_replay_aborted = true
+            // Try to finish fast
+            throw new Error('io replay aborted')
+          } else {
+            console.log('cached call found', call)
+            if(call.ok) {
+              // TODO resolve promises in the same order they were resolved on
+              // initial execution
+
+              if(call.value instanceof Promise) {
+                const original_setTimeout = globalThis.setTimeout.original
+                return Promise.all([
+                  call.value,
+                  new Promise(resolve => original_setTimeout(
+                    resolve,
+                    10
+                  ))
+                ]).then(([a,_]) => a)
+                  // TODO remove
+                  .then(x => {console.log('resolved',name); return x})
+              } else {
+                return call.value
+              }
+            } else {
+              throw call.error
+            }
+          }
+        }
+      }
+
+      Object.defineProperty(obj[method], 'name', {value: original.name})
+
+      obj[method].__original = original
+    }
+
+    function io_patch_remove(obj, method) {
+      if(obj == null || obj[method] == null) {
+        // Method is absent in current env, skip patching
+        return
+      }
+      obj[method] = obj[method].__original
+    }
+
+    const Response_methods = [
+      'arrayBuffer',
+      'blob',
+      'formData',
+      'json',
+      'text',
+    ]
+
+    function apply_io_patches() {
+      io_patch(Math, 'random', 'Math.random')
+
+
+      // TODO test
+      const Date = globalThis.Date
+      io_patch(globalThis, 'Date', 'Date')
+      globalThis.Date.parse =  Date.parse
+      globalThis.Date.now =    Date.now
+      globalThis.Date.UTC =    Date.UTC
+      globalThis.Date.length = Date.length
+      globalThis.Date.name =   Date.name
+      io_patch(globalThis.Date, 'now', 'Date.now')
+
+
+      io_patch(globalThis, 'fetch', 'fetch')
+      // Check if Response is defined, for node.js
+      if(globalThis.Response != null) {
+        for(let key of Response_methods) {
+          io_patch(Response.prototype, key, 'Response.prototype.' + key, true)
+        }
+      }
+
+      //TODO
+      const setTimeout = globalThis.setTimeout
+      globalThis.setTimeout = function(cb, timeout) {
+        const timer_id = setTimeout(function(...args) {
+          console.log('timeout', timer_id)
+          cb(...args)
+        }, timeout)
+        console.log('setTimeout', timer_id)
+        return timer_id
+      }
+      globalThis.setTimeout.original = setTimeout
+
+
+      // TODO clearTimeout
+    }
+
+    function remove_io_patches() {
+      // TODO when to apply io_patches and promise_patches? Only once, when we
+      // create window?
+
+      io_patch_remove(Math, 'random')
+      io_patch_remove(globalThis, 'Date')
+      io_patch_remove(globalThis, 'fetch')
+
+      // Check if Response is defined, for node.js
+      if(globalThis.Response != null) {
+        for(let key of Response_methods) {
+          io_patch_remove(Response.prototype, key)
+        }
+      }
+      globalThis.setTimeout = globalThis.setTimeout.original
+    }
+</script>
+
+<script type='module'>
+
+
+  //import {ethers} from 'https://unpkg.com/ethers/dist/ethers.esm.js'
+  import {ethers} from './ethers.js'
+
+  async function run() {
+
+    const URL = 'https://ethereum-goerli-rpc.allthatnode.com'
+
+    const p = ethers.getDefaultProvider(URL)
+
+    const latest = await p.getBlock()
+
+    const txs = await Promise.all(latest.transactions.slice(0,1).map(async (t, i) => {
+      console.error("GETTING RECEIPT", i)
+      const result = await p.getTransactionReceipt(t)
+      console.error("GOT RECEIPT", i)
+      return result
+    }))
+
+    const totalGas = txs.reduce((gas,tx) => 
+      gas.add(tx.gasUsed), ethers.BigNumber.from(0))
+
+    console.log('GAS', totalGas.add(3))
+  }
+
+
+  apply_io_patches()
+
+  await run()
+
+  io_cache_is_recording = false
+  console.error('REPLAY')
+  await run()
+
+
+</script>

record_io/fetch.html

@@ -0,0 +1,28 @@
+<script type='module'>
+
+const original = globalThis.fetch
+globalThis.fetch = function(...args) {
+  console.log('fetch called')
+  return original.apply(null, args)
+}
+
+for(let key of [
+                'arrayBuffer',
+                'blob',
+                'formData',
+                'json',
+                'text',
+               ]) {
+
+  let original = Response.prototype[key]
+  Response.prototype[key] = function(...args){
+    console.log('key called', key)
+    return original.apply(this, args)
+  }
+}
+
+console.log((await (await fetch('/')).text()).length)
+
+
+
+</script>

record_io/microtask_test.js

@@ -0,0 +1,26 @@
+console.log('start')
+
+let r
+const x = new Promise(resolve => r = resolve).then(() => {console.log('resolved')})
+
+console.log('before resolve')
+r()
+console.log('after resolve')
+/*
+console.log('start')
+
+Promise.resolve().then(() => {
+  console.log('1')
+  Promise.resolve().then(() => {
+    console.log('2')
+  })
+})
+
+console.log('end')
+Promise.resolve().then(() => {
+  console.log('3')
+  Promise.resolve().then(() => {
+    console.log('4')
+  })
+})
+*/

record_io/new.js

@@ -0,0 +1,16 @@
+/*
+function f() {
+  console.log('n', new.target)
+}
+
+f()
+new f()
+*/
+
+const f = new Function(`
+  return arguments.length
+`)
+
+
+console.log(f(1,2,3))
+console.log(f(1,2,3,4))

record_io/promise.js

@@ -0,0 +1,33 @@
+//let value = Promise.reject(1)
+
+/*
+value.then(
+  () => console.log('res'),
+  () => console.log('rej'),
+)
+*/
+
+
+/*
+const original_value = value
+
+value = new Promise((resolve, reject) => {
+  globalThis.setTimeout(
+    () => {
+      console.log('timeout')
+      original_value.then(resolve, reject)
+    },
+    1000
+  )
+})
+
+try {
+  console.log(await value)
+} catch(e) {
+  console.log('ERROR', e)
+}
+*/
+
+const t = globalThis.setTimeout
+
+t(() => console.log('timeout'), 100)

record_io/timelime

@@ -0,0 +1,73 @@
+Timeline                         Replay
+
+call a()                         call a()
+resolve a()
+
+call b()
+resolve b()
+                                                 
+call c()
+resolve c()
+
+
+Timeline                         Replay                                              
+
+																 resolution_index = 0, io_index = 0 
+
+call a()                         call a: return promise
+																   compare resolutions[resolution_index] with io_index
+																	 io_index < resolutions[0]
+																	 do not resolve
+																	 io_index++
+
+call b()                         call b: return promise
+																   compare resolutions[0] && io_index
+																	 io_index < resolutions[0]
+																	 do not resolve
+
+call c()                         call c: return promise                        
+                                                 
+resolve c()                                                 
+resolve b()                                                 
+resolve a()                                                 
+
+
+resolutions: [
+  3,
+  2,
+  1,
+]
+
+Делаем реплей. К нам приходят события - вызовы функций. Мы перехватываем вызов, возвращаем промис, и ресолвим тот промис, который сейчас надо заресолвить. Например, в примере выше мы ресолвим a() после вызова с(). А b() ресолвим после ресолва с(). То есть мы можем ресолвить несколько за раз.
+
+
+
+Record: [
+  call a 
+  resolve a
+  call b
+  resolve b
+]
+
+Replay: [
+
+   call a
+   смотрим что возвращается промис, взводим ресолвер
+   
+   ресолвер сработал
+   resolve a
+
+   call b
+   смотрим что возвращается промис, взводим ресолвер
+
+   ресолвер сработал
+   resolve b
+]
+
+
+
+
+
+
+call
+resolve

src/cmd.js

@@ -52,6 +52,7 @@ const apply_eval_result = (state, eval_result) => {
       log_position: null
     },
     modules: eval_result.modules,
+    io_cache: eval_result.io_cache,
   }
 }
 
@@ -197,6 +198,7 @@ const external_imports_loaded = (
       external_imports,
       state.on_deferred_call,
       state.calltree_changed_token,
+      state.io_cache,
     )
     toplevel = true
   } else {
@@ -205,6 +207,7 @@ const external_imports_loaded = (
       external_imports,
       state.on_deferred_call,
       state.calltree_changed_token,
+      state.io_cache,
       {index: node.index, module: state.current_module},
     )
     toplevel = false

src/eval.js

@@ -287,6 +287,7 @@ export const eval_modules = (
   external_imports, 
   on_deferred_call,
   calltree_changed_token,
+  io_cache,
   location
 ) => {
   // TODO gensym __cxt, __trace, __trace_call
@@ -295,6 +296,23 @@ export const eval_modules = (
 
   const is_async = has_toplevel_await(parse_result.modules)
 
+  const Function = is_async
+    ? globalThis.run_window.eval('(async function(){})').constructor
+    : globalThis.run_window.Function
+
+  const module_fns = parse_result.sorted.map(module => (
+    {
+      module,
+      fn: new Function(
+        '__cxt',
+        '__trace',
+        '__trace_call',
+        '__do_await',
+        codegen(parse_result.modules[module], {module})
+      )
+    }
+  ))
+
   const cxt = {
     modules: external_imports == null
       ? {}
@@ -325,24 +343,7 @@ export const eval_modules = (
     Promise: globalThis.run_window.Promise,
   }
 
-  const Function = is_async
-    ? globalThis.run_window.eval('(async function(){})').constructor
-    : globalThis.run_window.Function
-
-  const module_fns = parse_result.sorted.map(module => (
-    {
-      module,
-      fn: new Function(
-        '__cxt',
-        '__trace',
-        '__trace_call',
-        '__do_await',
-        codegen(parse_result.modules[module], {module})
-      )
-    }
-  ))
-
-  const result = run(module_fns, cxt)
+  const result = run(module_fns, cxt, io_cache)
 
   const make_result = result => ({
     modules: result.modules,
@@ -350,14 +351,14 @@ export const eval_modules = (
     eval_cxt: result.eval_cxt,
     calltree: assign_code(parse_result.modules, result.calltree),
     call: result.call && assign_code(parse_result.modules, result.call),
+    io_cache: result.eval_cxt.io_cache,
   })
 
-  if(result.then != null) {
+  if(is_async) {
     return result.then(make_result)
   } else {
     return make_result(result)
   }
-
 }
 
 export const eval_find_call = (cxt, parse_result, calltree, location) => {

src/globals.js

@@ -1 +1,4 @@
 export const globals = new Set(Object.getOwnPropertyNames(globalThis))
+
+// Not available in node.js, but add to use in tests
+globals.add('fetch')

src/record_io.js

@@ -0,0 +1,268 @@
+import {set_record_call} from './runtime.js'
+ 
+const io_patch = (cxt, obj, method, name, use_context = false) => {
+  if(obj == null || obj[method] == null) {
+    // Method is absent in current env, skip patching
+    return
+  }
+  const original = obj[method]
+  obj[method] = function(...args) {
+    // TODO guard calls from prev run
+    console.error('patched method', name, {
+        io_cache_is_recording: cxt.io_cache_is_recording, 
+        io_cache_is_replay_aborted: cxt.io_cache_is_replay_aborted, 
+        io_cache_index: cxt.io_cache_is_recording
+          ? cxt.io_cache.length
+          : cxt.io_cache_index
+    })
+    // TODO guard that in find_call io methods are not called?
+    // if(searched_location != null) {
+    //   throw new Error('illegal state')
+    // }
+    if(cxt.io_cache_is_replay_aborted) {
+      // Try to finish fast
+      throw new Error('io recording aborted')
+    } else if(cxt.io_cache_is_recording) {
+      let ok, value, error
+      const has_new_target = new.target != null
+      try {
+        // TODO. Do we need it here? Only need for IO calls view. And also
+        // for expand_call and find_call, to not use cache on expand call
+        // and find_call
+        set_record_call(cxt)
+
+        const index = cxt.io_cache.length
+
+        if(name == 'setTimeout') {
+          args = args.slice()
+          // Patch callback
+          const cb = args[0]
+          args[0] = function() {
+            // TODO guard calls from prev runs
+            // TODO guard io_cache_is_replay_aborted
+            cxt.io_cache.push({type: 'resolution', index})
+            cb()
+          }
+        }
+
+        value = has_new_target 
+          ? new original(...args)
+          : original.apply(this, args)
+
+        console.log('value', value)
+
+        if(value instanceof Promise) {
+          // TODO use native .finally for promise, not patched then?
+          value.finally(() => {
+            // TODO guard calls from prev runs
+            // TODO guard io_cache_is_replay_aborted
+            cxt.io_cache.push({type: 'resolution', index})
+          })
+        }
+
+        ok = true
+        return value
+      } catch(e) {
+        error = e
+        ok = false
+        throw e
+      } finally {
+        cxt.io_cache.push({
+          type: 'call',
+          name,
+          ok, 
+          value, 
+          error, 
+          args, 
+          // To discern calls with and without 'new' keyword, primary for
+          // Date that can be called with and without new
+          has_new_target,
+          use_context,
+          context: use_context ? this : undefined,
+        })
+      }
+    } else {
+      const call = cxt.io_cache[cxt.io_cache_index]
+      /*
+      TODO remove
+      console.log(
+        call.type != 'call'
+        , call == null
+        , call.has_new_target != (new.target != null)
+        , call.use_context && (call.context != this)
+        , call.name != name
+        , JSON.stringify(call.args) != JSON.stringify(args)
+      )
+      */
+
+      // TODO if call.type != 'call', and there are no more calls, should
+      // we abort, or just record one more call?
+
+      if(
+        call == null
+        || call.type != 'call'
+        || call.has_new_target != (new.target != null)
+          // TODO test
+        || call.use_context && (call.context != this)
+        || call.name != name
+        || (
+            // TODO for setTimeout, compare last arg (timeout)
+            name != 'setTimeout' 
+            && 
+            JSON.stringify(call.args) != JSON.stringify(args)
+           )
+      ){
+        console.log('discard cache', call)
+        cxt.io_cache_is_replay_aborted = true
+        // Try to finish fast
+        throw new Error('io replay aborted')
+      } else {
+        console.log('cached call found', call)
+        const next_resolution = cxt.io_cache.find((e, i) => 
+          e.type == 'resolution' && i > cxt.io_cache_index
+        )
+
+        if(next_resolution != null && !cxt.io_cache_resolver_is_set) {
+          console.error('set resolver')
+          const original_setTimeout = globalThis.setTimeout.__original
+          cxt.io_cache_resolver_is_set = true
+
+          original_setTimeout(() => {
+            // TODO guard from previous run
+            console.error('resolver', {
+              io_cache_is_replay_aborted: cxt.io_cache_is_replay_aborted,
+              io_cache_index: cxt.io_cache_index,
+            })
+
+            cxt.io_cache_resolver_is_set = false
+
+            // TODO check if call from prev run 
+
+            if(cxt.io_cache_is_replay_aborted) {
+              return
+            }
+
+            if(cxt.io_cache_index >= cxt.io_cache.length) {
+              // TODO Do nothing or what?
+              // Should not gonna happen
+              throw new Error('illegal state')
+            } else {
+              const next_event = cxt.io_cache[cxt.io_cache_index]
+              if(next_event.type == 'call') {
+                // TODO Call not happened, replay?
+                cxt.io_cache_is_replay_aborted = true
+              } else {
+                while(
+                  cxt.io_cache_index < cxt.io_cache.length 
+                  && 
+                  cxt.io_cache[cxt.io_cache_index].type == 'resolution'
+                ) {
+                  const resolution = cxt.io_cache[cxt.io_cache_index]
+                  const resolver = cxt.io_cache_resolvers.get(resolution.index)
+
+                  cxt.io_cache_index++
+
+                  if(cxt.io_cache[resolution.index].name == 'setTimeout') {
+                    resolver()
+                  } else {
+                    resolver(cxt.io_cache[resolution.index].value)
+                  }
+                  console.log('RESOLVE', cxt.io_cache_index, resolution.index)
+                }
+              }
+            }
+
+            }, 0)
+        }
+
+        cxt.io_cache_index++
+
+        if(call.ok) {
+          // TODO resolve promises in the same order they were resolved on
+          // initial execution
+
+          if(call.value instanceof Promise) {
+            return new Promise(resolve => {
+              cxt.io_cache_resolvers.set(cxt.io_cache_index - 1, resolve)
+            })
+          } else if(name == 'setTimeout') {
+            const timeout_cb = args[0]
+            cxt.io_cache_resolvers.set(cxt.io_cache_index - 1, timeout_cb)
+            return call.value
+          } else {
+            return call.value
+          }
+        } else {
+          throw call.error
+        }
+      }
+    }
+  }
+
+  Object.defineProperty(obj[method], 'name', {value: original.name})
+
+  obj[method].__original = original
+}
+
+const io_patch_remove = (obj, method) => {
+  if(obj == null || obj[method] == null) {
+    // Method is absent in current env, skip patching
+    return
+  }
+  obj[method] = obj[method].__original
+}
+
+const Response_methods = [
+  'arrayBuffer',
+  'blob',
+  'formData',
+  'json',
+  'text',
+]
+
+export const apply_io_patches = cxt => {
+  io_patch(cxt, Math, 'random', 'Math.random')
+
+  io_patch(cxt, globalThis, 'setTimeout', 'setTimeout')
+  // TODO test
+  io_patch(cxt, globalThis, 'clearTimeout', 'clearTimeout')
+
+
+  // TODO test
+  const Date = globalThis.Date
+  io_patch(cxt, globalThis, 'Date', 'Date')
+  globalThis.Date.parse =  Date.parse
+  globalThis.Date.now =    Date.now
+  globalThis.Date.UTC =    Date.UTC
+  io_patch(cxt, globalThis.Date, 'now', 'Date.now')
+
+
+  io_patch(cxt, globalThis, 'fetch', 'fetch')
+  // Check if Response is defined, for node.js
+  if(globalThis.Response != null) {
+    for(let key of Response_methods) {
+      io_patch(cxt, Response.prototype, key, 'Response.prototype.' + key, true)
+    }
+  }
+}
+
+export const remove_io_patches = cxt => {
+  // TODO when to apply io_patches and promise_patches? Only once, when we
+  // create window?
+
+  io_patch_remove(Math, 'random')
+
+  io_patch_remove(globalThis, 'setTimeout')
+  // TODO test
+  io_patch_remove(globalThis, 'clearTimeout')
+
+  io_patch_remove(globalThis, 'Date')
+  io_patch_remove(globalThis, 'fetch')
+
+  // Check if Response is defined, for node.js
+  if(globalThis.Response != null) {
+    for(let key of Response_methods) {
+      io_patch_remove(Response.prototype, key)
+    }
+  }
+}

src/runtime.js

@@ -1,3 +1,5 @@
+import {apply_io_patches, remove_io_patches} from './record_io.js'
+
 /*
 Converts generator-returning function to promise-returning function. Allows to
 have the same code both for sync and async. If we have only sync modules (no
@@ -27,10 +29,27 @@ const gen_to_promise = gen_fn => {
   }
 }
 
-export const run = gen_to_promise(function*(module_fns, cxt){
+const do_run = function*(module_fns, cxt, io_cache){
   let calltree
 
+  cxt = io_cache == null
+    // TODO move all io_cache properties to the object?
+    ? {...cxt,
+      io_cache_is_recording: true,
+      io_cache: [],
+    }
+    : {...cxt,
+      io_cache_is_recording: false,
+      io_cache,
+      io_cache_resolver_is_set: false,
+      // Map of (index in io_cache) -> resolve
+      io_cache_resolvers: new Map(),
+      io_cache_is_replay_aborted: false,
+      io_cache_index: 0,
+    }
+
   apply_promise_patch(cxt)
+  apply_io_patches(cxt)
 
   for(let {module, fn} of module_fns) {
      cxt.found_call = null
@@ -60,6 +79,7 @@ export const run = gen_to_promise(function*(module_fns, cxt){
   cxt.logs = []
   cxt.children = null
 
+  remove_io_patches(cxt)
   remove_promise_patch(cxt)
 
   cxt.searched_location = null
@@ -73,6 +93,20 @@ export const run = gen_to_promise(function*(module_fns, cxt){
     logs: _logs,
     eval_cxt: cxt,
   }
+}
+
+export const run = gen_to_promise(function*(module_fns, cxt, io_cache) {
+  const result = yield* do_run(module_fns, cxt, io_cache)
+
+  if(result.eval_cxt.io_cache_is_replay_aborted) {
+    // TODO test next line
+    result.eval_cxt.is_recording_deferred_calls = false
+
+    // run again without io cache
+    return yield* do_run(module_fns, cxt, null)
+  } else {
+    return result
+  }
 })
 
 const apply_promise_patch = cxt => {
@@ -113,7 +147,7 @@ const remove_promise_patch = cxt => {
   cxt.Promise.prototype.then = cxt.promise_then
 }
 
-const set_record_call = cxt => {
+export const set_record_call = cxt => {
   for(let i = 0; i < cxt.stack.length; i++) {
     cxt.stack[i] = true
   }

test/test.js

@@ -21,6 +21,7 @@ import {
   test_initial_state, test_initial_state_async,
   test_deferred_calls_state,
   print_debug_ct_node,
+  command_input_async,
 } from './utils.js'
 
 export const tests = [
@@ -2957,17 +2958,9 @@ const y = x()`
       }
       await f()
     `
-    const {state: after_edit} = COMMANDS.input(i, code2, code2.indexOf('1'))
-    const result = await after_edit.eval_modules_state.promise
-    const after_edit_finished = COMMANDS.eval_modules_finished(
-      after_edit, 
-      after_edit,
-      result, 
-      after_edit.eval_modules_state.node, 
-      after_edit.eval_modules_state.toplevel
-    )
-    assert_equal(after_edit_finished.active_calltree_node.fn.name, 'f')
-    assert_equal(after_edit_finished.value_explorer.result.value, 1)
+    const next = await command_input_async(i, code2, code2.indexOf('1'))
+    assert_equal(next.active_calltree_node.fn.name, 'f')
+    assert_equal(next.value_explorer.result.value, 1)
   }),
 
   test('async/await move_cursor', async () => {
@@ -3019,4 +3012,135 @@ const y = x()`
     // No assertion, must not throw
   }),
 
+  test('record io', () => {
+    const random = globalThis.run_window.Math.random
+
+    // Patch Math.random to always return 1
+    Object.assign(globalThis.run_window.Math, {random: () => 1})
+
+    const initial = test_initial_state(`
+      const x = Math.random()
+    `)
+    
+    // Now call to Math.random is cached, break it to ensure it was not called
+    // on next run
+    Object.assign(globalThis.run_window.Math, {random: () => { throw 'fail' }})
+
+    const next = COMMANDS.input(initial, `const x = Math.random()*2`, 0).state
+    assert_equal(next.value_explorer.result.value, 2)
+
+    // Patch Math.random to return 2. Now the first call to Math.random() is
+    // cached with value 1, and the second shoud return 2
+    Object.assign(globalThis.run_window.Math, {random: () => 2})
+    const replay_failed = COMMANDS.input(
+      initial, 
+      `const x = Math.random() + Math.random()`, 
+      0
+    ).state
+    // TODO must reuse first cached call?
+    assert_equal(replay_failed.value_explorer.result.value, 4)
+
+    // Remove patch
+    Object.assign(globalThis.run_window.Math, {random})
+  }),
+
+  test('record io preserve promise resolution order', async () => {
+    const original_fetch = globalThis.run_window.fetch
+
+    // Generate fetch function which calls get resolved in reverse order
+    const {fetch, resolve} = new Function(`
+      const calls = []
+      return {
+        fetch(...args) {
+          let resolver
+          const promise = new Promise(r => resolver = r)
+          calls.push({resolver, promise, args})
+          console.log('patched fetch called')
+          return promise
+        },
+
+        resolve() {
+          console.log('resolve', calls);
+          [...calls].reverse().forEach(call => call.resolver(...call.args))
+        },
+      }
+    `)()
+
+    // Patch fetch
+    Object.assign(globalThis.run_window, {fetch})
+
+    const initial_promise = test_initial_state_async(`
+      const result = {}
+      await Promise.all(
+        [1, 2, 3].map(async v => Object.assign(result, {value: await fetch(v)}))
+      )
+      console.log(result)
+    `)
+
+    resolve()
+
+    const initial = await initial_promise
+
+    // calls to fetch are resolved in reverse order, so first call wins
+    assert_equal(initial.logs.logs[0].args[0].value, 1)
+
+    // Break fetch to ensure it does not get called anymore
+    Object.assign(globalThis.run_window, {fetch: () => {throw 'broken'}})
+
+    const with_cache = await command_input_async(
+      initial, 
+      `
+        const result = {}
+        await Promise.all(
+          [1, 2, 3].map(async v => 
+            Object.assign(result, {value: await fetch(v)})
+          )
+        )
+        console.log(result)
+      `,
+      0
+    )
+
+    // cached calls to fetch shoudl be resolved in the same (reverse) order as
+    // on the first run, so first call wins
+    assert_equal(with_cache.logs.logs[0].args[0].value, 1)
+
+    // Remove patch
+    Object.assign(globalThis.run_window, {fetch: original_fetch})
+  }),
+
+  test('record io setTimeout', async () => {
+    const i = await test_initial_state_async(`
+      const delay = timeout => new Promise(resolve => 
+        setTimeout(() => resolve(1), timeout)
+      )
+      console.log(await delay(0))
+    `)
+
+    assert_equal(i.io_cache != null, true)
+    assert_equal(i.logs.logs[0].args[0], 1)
+
+    const code2 = `
+      const delay = timeout => new Promise(resolve => 
+        setTimeout(() => resolve(10), timeout)
+      )
+      console.log(await delay(0))
+    `
+
+    console.log('CODE2', code2.slice(75))
+
+    const next = await command_input_async(i, code2, 0)
+
+    // Assert cache was used
+    // TODO check that items were not appended
+    assert_equal(next.io_cache == i.io_cache, true)
+
+    assert_equal(next.logs.logs[0].args[0], 10)
+
+  }),
+
+  // TODO test resolution order with sync functions (Date, Math.random)
+
+
+
 ]

test/utils.js

@@ -39,7 +39,7 @@ export const assert_code_error = (codestring, error) => {
 export const assert_code_evals_to_async = async (codestring, expected) => {
   const s = await test_initial_state_async(codestring)
   const frame = active_frame(s)
-  const result = frame.children[frame.children.length - 1].result
+  const result = frame.children.at(-1).result
   assert_equal(result.ok, true)
   assert_equal(result.value, expected)
 }
@@ -78,6 +78,18 @@ export const test_initial_state_async = async code => {
   )
 }
 
+export const command_input_async = async (...args) => {
+  const after_input = COMMANDS.input(...args).state
+  const result = await after_input.eval_modules_state.promise
+  return COMMANDS.eval_modules_finished(
+    after_input, 
+    after_input,
+    result, 
+    after_input.eval_modules_state.node, 
+    after_input.eval_modules_state.toplevel
+  )
+}
+
 export const test_deferred_calls_state = code => {
   const {get_deferred_call, on_deferred_call} = (new Function(`
     let args