Implement subscriptions based on ethereumjs-blockstream

3 files changed, 81 insertions, 41 deletions

diff --git a/src/utils/constants.ts b/src/utils/constants.ts
index 1b11d7055..a066fe869 100644
--- a/src/utils/constants.ts
+++ b/src/utils/constants.ts
@@ -7,4 +7,5 @@ export const constants = {
     INVALID_JUMP_PATTERN: 'invalid JUMP at',
     OUT_OF_GAS_PATTERN: 'out of gas',
     UNLIMITED_ALLOWANCE_IN_BASE_UNITS: new BigNumber(2).pow(256).minus(1),
+    DEFAULT_BLOCK_POLLING_INTERVAL: 1000,
 };
diff --git a/src/utils/event_utils.ts b/src/utils/event_utils.ts
deleted file mode 100644
index e8f30e1a8..000000000
--- a/src/utils/event_utils.ts
+++ /dev/null
@@ -1,41 +0,0 @@
-import * as _ from 'lodash';
-import {EventCallback, ContractEventArg, ContractEvent, ContractEventObj, ContractEventEmitter} from '../types';
-import * as BigNumber from 'bignumber.js';
-import promisify = require('es6-promisify');
-
-export const eventUtils = {
-    wrapEventEmitter(event: ContractEventObj): ContractEventEmitter {
-        const watch = (eventCallback: EventCallback) => {
-            const bignumberWrappingEventCallback = eventUtils._getBigNumberWrappingEventCallback(eventCallback);
-            event.watch(bignumberWrappingEventCallback);
-        };
-        const zeroExEvent = {
-            watch,
-            stopWatchingAsync: async () => {
-                await promisify(event.stopWatching, event)();
-            },
-        };
-        return zeroExEvent;
-    },
-    /**
-     * Wraps eventCallback function so that all the BigNumber arguments are wrapped in a newer version of BigNumber.
-     * @param eventCallback     Event callback function to be wrapped
-     * @return Wrapped event callback function
-     */
-    _getBigNumberWrappingEventCallback(eventCallback: EventCallback): EventCallback {
-        const bignumberWrappingEventCallback = (err: Error, event: ContractEvent) => {
-            if (_.isNull(err)) {
-                const wrapIfBigNumber = (value: ContractEventArg): ContractEventArg => {
-                    // HACK: The old version of BigNumber used by Web3@0.19.0 does not support the `isBigNumber`
-                    // and checking for a BigNumber instance using `instanceof` does not work either. We therefore
-                    // check if the value constructor is a bignumber constructor.
-                    const isWeb3BigNumber = _.startsWith(value.constructor.toString(), 'function BigNumber(');
-                    return isWeb3BigNumber ?  new BigNumber(value) : value;
-                };
-                event.args = _.mapValues(event.args, wrapIfBigNumber);
-            }
-            eventCallback(err, event);
-        };
-        return bignumberWrappingEventCallback;
-    },
-};
diff --git a/src/utils/filter_utils.ts b/src/utils/filter_utils.ts
new file mode 100644
index 000000000..ee39b6836
--- /dev/null
+++ b/src/utils/filter_utils.ts
@@ -0,0 +1,80 @@
+import * as _ from 'lodash';
+import * as Web3 from 'web3';
+import * as uuid from 'uuid/v4';
+import * as ethUtil from 'ethereumjs-util';
+import {ContractEvents, IndexedFilterValues, SubscriptionOpts} from '../types';
+
+const TOPIC_LENGTH = 32;
+
+export const filterUtils = {
+    generateUUID(): string {
+        return uuid();
+    },
+    getFilter(keccak256: (data: string) => string, address: string, eventName: ContractEvents,
+              indexFilterValues: IndexedFilterValues, abi: Web3.ContractAbi,
+              subscriptionOpts?: SubscriptionOpts): Web3.FilterObject {
+        const eventAbi = _.find(abi, {name: eventName}) as Web3.EventAbi;
+        const eventSignature = filterUtils.getEventSignatureFromAbiByName(eventAbi, eventName);
+        const topicForEventSignature = keccak256(eventSignature);
+        const topicsForIndexedArgs = filterUtils.getTopicsForIndexedArgs(eventAbi, indexFilterValues);
+        const topics = [topicForEventSignature, ...topicsForIndexedArgs];
+        let filter: Web3.FilterObject = {
+            address,
+            topics,
+        };
+        if (!_.isUndefined(subscriptionOpts)) {
+            filter = {
+                ...subscriptionOpts,
+                ...filter,
+            };
+        }
+        return filter;
+    },
+    getEventSignatureFromAbiByName(eventAbi: Web3.EventAbi, eventName: ContractEvents): string {
+        const types = _.map(eventAbi.inputs, 'type');
+        const signature = `${eventAbi.name}(${types.join(',')})`;
+        return signature;
+    },
+    getTopicsForIndexedArgs(abi: Web3.EventAbi, indexFilterValues: IndexedFilterValues): Array<string|null> {
+        const topics: Array<string|null> = [];
+        for (const eventInput of abi.inputs) {
+            if (!eventInput.indexed) {
+                continue;
+            }
+            if (_.isUndefined(indexFilterValues[eventInput.name])) {
+                topics.push(null);
+            } else {
+                const value = indexFilterValues[eventInput.name] as string;
+                const buffer = ethUtil.toBuffer(value);
+                const paddedBuffer = ethUtil.setLengthLeft(buffer, TOPIC_LENGTH);
+                const topic = ethUtil.bufferToHex(paddedBuffer);
+                topics.push(topic);
+            }
+        }
+        return topics;
+    },
+    matchesFilter(log: Web3.LogEntry, filter: Web3.FilterObject): boolean {
+        if (!_.isUndefined(filter.address) && log.address !== filter.address) {
+            return false;
+        }
+        if (!_.isUndefined(filter.topics)) {
+            return filterUtils.matchesTopics(log.topics, filter.topics);
+        }
+        return true;
+    },
+    matchesTopics(logTopics: string[], filterTopics: Array<string[]|string|null>): boolean {
+        const matchesTopic = _.zipWith(logTopics, filterTopics, filterUtils.matchesTopic.bind(filterUtils));
+        const matchesTopics = _.every(matchesTopic);
+        return matchesTopics;
+    },
+    matchesTopic(logTopic: string, filterTopic: string[]|string|null): boolean {
+        if (_.isArray(filterTopic)) {
+            return _.includes(filterTopic, logTopic);
+        }
+        if (_.isString(filterTopic)) {
+            return filterTopic === logTopic;
+        }
+        // null topic is a wildcard
+        return true;
+    },
+};