cache the preimages for a debug session (using the initial state)

src/solidity/types/Mapping.js

@@ -11,12 +11,13 @@ class Mapping extends RefType {
   }
 
   async decodeFromStorage (location, storageResolver) {
+    var mappingsPreimages
     try {
-      var mappingsPreimages = await storageResolver.mappingPreimages()
+      mappingsPreimages = await storageResolver.mappingsLocation()
     } catch (e) {
       return {
-        value: '<error> ' + e.message,
-        type: this.type
+        value: e.message,
+        type: this.typeName
       }
     }
     var mapSlot = util.normalizeHex(ethutil.bufferToHex(location.slot))

src/storage/mappingPreimages.js

 var global = require('../helpers/global')
 
 module.exports = {
-  extractMappingPreimages: extractMappingPreimages
+  decodeMappingsKeys: decodeMappingsKeys
 }
 
 /**
- * Uses the storageViewer to retrieve the storage and returns a mapping containing possible solidity mappping type location.
- * like { "<mapping_slot>" : { "<mapping-key1>": preimageOf1 }, { "<mapping-key2>": preimageOf2 }, ... }
- *
- * @param {Object} address  - storageViewer
- * @return {Map} - solidity mapping location
- */
-async function extractMappingPreimages (storageViewer) {
-  return new Promise((resolve, reject) => {
-    storageViewer.storageRange(function (error, storage) {
-      if (!error) {
-        decodeMappingsKeys(storage, (error, mappings) => {
-          if (error) {
-            reject(error)
-          } else {
-            resolve(mappings)
-          }
-        })
-      } else {
-        reject(error)
-      }
-    })
-  })
-}
-
-/**
- * Uses the storageViewer to retrieve the storage and returns a mapping containing possible solidity mappping type location.
+  * extract the mappings location from the storage
   * like { "<mapping_slot>" : { "<mapping-key1>": preimageOf1 }, { "<mapping-key2>": preimageOf2 }, ... }
   *
   * @param {Object} storage  - storage given by storage Viewer (basically a mapping hashedkey : {key, value})

src/storage/storageResolver.js

 'use strict'
 var traceHelper = require('../helpers/traceHelper')
 var util = require('../helpers/global')
+var mappingPreimages = require('./mappingPreimages')
 
+/**
+  * Basically one instance is created for one debugging session.
+  * (TODO: one instance need to be shared over all the components)
+  */
 class StorageResolver {
   constructor () {
     this.storageByAddress = {}
+    this.preimagesMappingByAddress = {}
     this.maxSize = 100
   }
 
@@ -22,6 +28,33 @@ class StorageResolver {
   }
 
   /**
+    * compute the mappgings type locations for the current address (cached for a debugging session)
+    * note: that only retrieve the first 100 items.
+    *
+    * @param {String} address  - contract address
+    * @param {Object} address  - storage
+    * @return {Function} - callback
+    */
+  initialPreimagesMappings (tx, stepIndex, address, callback) {
+    if (this.preimagesMappingByAddress[address]) {
+      return callback(null, this.preimagesMappingByAddress[address])
+    }
+    this.storageRange(tx, stepIndex, address, (error, storage) => {
+      if (error) {
+        return callback(error)
+      }
+      mappingPreimages.decodeMappingsKeys(storage, (error, mappings) => {
+        if (error) {
+          callback(error)
+        } else {
+          this.preimagesMappingByAddress[address] = mappings
+          callback(null, mappings)
+        }
+      })
+    })
+  }
+
+  /**
     * return a slot value for the given context (address and vm trace index)
     *
     * @param {String} - slot - slot key

src/storage/storageViewer.js

 'use strict'
 var helper = require('../helpers/util')
-var mappingPreimagesExtractor = require('./mappingPreimages')
+var mappingPreimages = require('./mappingPreimages')
 
+ /**
+   * easier access to the storage resolver
+   * Basically one instance is created foreach execution step and foreach component that need it.
+   * (TODO: one instance need to be shared over all the components)
+   */
 class StorageViewer {
   constructor (_context, _storageResolver, _traceManager) {
     this.context = _context
     this.storageResolver = _storageResolver
-    // contains [mappingSlot][mappingkey] = preimage
-    // this map is renewed for each execution step
-    // this map is shared among all the mapping types
-    this.mappingsPreimages = null
     _traceManager.accumulateStorageChanges(this.context.stepIndex, this.context.address, {}, (error, storageChanges) => {
       if (!error) {
         this.storageChanges = storageChanges
@@ -64,12 +65,58 @@ class StorageViewer {
     return this.storageResolver.isComplete(address)
   }
 
-  async mappingPreimages () {
-    if (!this.mappingsPreimages) {
-      this.mappingsPreimages = await mappingPreimagesExtractor.extractMappingPreimages(this)
+  /**
+    * return all the possible mappings locations for the current context (cached)
+    *
+    * @param {Function} callback
+    */
+  async mappingsLocation () {
+    return new Promise((resolve, reject) => {
+      if (this.completeMappingsLocation) {
+        return resolve(this.completeMappingsLocation)
+      }
+      this.storageResolver.initialPreimagesMappings(this.context.tx, this.context.stepIndex, this.context.address, (error, initialMappingsLocation) => {
+        if (error) {
+          reject(error)
+        } else {
+          this.extractMappingsLocationChanges(this.storageChanges, (error, mappingsLocationChanges) => {
+            if (error) {
+              return reject(error)
+            }
+            this.completeMappingsLocation = Object.assign({}, initialMappingsLocation)
+            for (var key in mappingsLocationChanges) {
+              if (!initialMappingsLocation[key]) {
+                initialMappingsLocation[key] = {}
+              }
+              this.completeMappingsLocation[key] = Object.assign({}, initialMappingsLocation[key], mappingsLocationChanges[key])
+            }
+            resolve(this.completeMappingsLocation)
+          })
+        }
+      })
+    })
+  }
+
+  /**
+    * retrieve mapping location changes from the storage changes.
+    *
+    * @param {Function} callback
+    */
+  extractMappingsLocationChanges (storageChanges, callback) {
+    if (this.mappingsLocationChanges) {
+      return callback(null, this.mappingsLocationChanges)
     }
-    return this.mappingsPreimages
+    mappingPreimages.decodeMappingsKeys(storageChanges, (error, mappings) => {
+      if (!error) {
+        this.mappingsLocationChanges = mappings
+        return callback(null, this.mappingsLocationChanges)
+      } else {
+        callback(error)
+      }
+    })
   }
 }
 
+
+
 module.exports = StorageViewer