cache improvement solves #219

packages/api/src/controllers/queryHistory.js

@@ -48,7 +48,7 @@ module.exports = {
   async write({ data }) {
     const fileName = path.join(datadir(), 'query-history.jsonl');
     await fs.appendFile(fileName, JSON.stringify(data) + '\n');
-    socket.emitChanged('query-history-changed');
+    socket.emit('query-history-changed');
     return 'OK';
   },
 };

packages/api/src/utility/socket.js

@@ -23,7 +23,7 @@ module.exports = {
     }
   },
   emitChanged(key) {
-    this.emit('clean-cache', key);
+    this.emit('changed-cache', key);
-    this.emit(key);
+    // this.emit(key);
   },
 };

packages/web/src/utility/api.ts

@@ -1,11 +1,11 @@
 import resolveApi, { resolveApiHeaders } from './resolveApi';
 import { writable } from 'svelte/store';
-import { cacheClean } from './cache';
+// import { cacheClean } from './cache';
 import getElectron from './getElectron';
 // import socket from './socket';
 
 let eventSource;
-let cacheCleanerRegistered;
+// let cacheCleanerRegistered;
 
 function wantEventSource() {
   if (!eventSource) {
@@ -60,10 +60,10 @@ export function apiOn(event: string, handler: Function) {
     eventSource.addEventListener(event, apiHandlers.get(handler));
   }
 
-  if (!cacheCleanerRegistered) {
+  // if (!cacheCleanerRegistered) {
-    cacheCleanerRegistered = true;
+  //   cacheCleanerRegistered = true;
-    apiOn('clean-cache', reloadTrigger => cacheClean(reloadTrigger));
+  //   apiOn('clean-cache', reloadTrigger => cacheClean(reloadTrigger));
-  }
+  // }
 }
 
 export function apiOff(event: string, handler: Function) {

packages/web/src/utility/cache.ts

@@ -1,40 +1,120 @@
+import { apiOn } from './api';
 import getAsArray from './getAsArray';
 
-let cachedByKey = {};
+const cachedByKey = {};
-let cachedPromisesByKey = {};
+const cachedPromisesByKey = {};
 const cachedKeysByReloadTrigger = {};
+const subscriptionsByReloadTrigger = {};
+const cacheGenerationByKey = {};
 
-export function cacheGet(key) {
+let cacheGeneration = 0;
+
+function cacheGet(key) {
   return cachedByKey[key];
 }
 
-export function cacheSet(key, value, reloadTrigger) {
+function addCacheKeyToReloadTrigger(cacheKey, reloadTrigger) {
-  cachedByKey[key] = value;
   for (const item of getAsArray(reloadTrigger)) {
     if (!(item in cachedKeysByReloadTrigger)) {
       cachedKeysByReloadTrigger[item] = [];
     }
-    cachedKeysByReloadTrigger[item].push(key);
+    cachedKeysByReloadTrigger[item].push(cacheKey);
   }
-  delete cachedPromisesByKey[key];
 }
 
-export function cacheClean(reloadTrigger) {
+function cacheSet(cacheKey, value, reloadTrigger, generation) {
+  cachedByKey[cacheKey] = value;
+  addCacheKeyToReloadTrigger(cacheKey, reloadTrigger);
+  delete cachedPromisesByKey[cacheKey];
+  cacheGenerationByKey[cacheKey] = generation;
+}
+
+function cacheClean(reloadTrigger) {
+  cacheGeneration += 1;
   for (const item of getAsArray(reloadTrigger)) {
     const keys = cachedKeysByReloadTrigger[item];
     if (keys) {
       for (const key of keys) {
         delete cachedByKey[key];
         delete cachedPromisesByKey[key];
+        cacheGenerationByKey[key] = cacheGeneration;
       }
     }
     delete cachedKeysByReloadTrigger[item];
   }
 }
 
-export function getCachedPromise(key, func) {
+function getCachedPromise(reloadTrigger, cacheKey, func) {
-  if (key in cachedPromisesByKey) return cachedPromisesByKey[key];
+  if (cacheKey in cachedPromisesByKey) return cachedPromisesByKey[cacheKey];
   const promise = func();
-  cachedPromisesByKey[key] = promise;
+  cachedPromisesByKey[cacheKey] = promise;
+  addCacheKeyToReloadTrigger(cacheKey, reloadTrigger);
   return promise;
 }
+
+function acquireCacheGeneration() {
+  cacheGeneration += 1;
+  return cacheGeneration;
+}
+
+function getCacheGenerationForKey(cacheKey) {
+  return cacheGenerationByKey[cacheKey] || 0;
+}
+
+export async function loadCachedValue(reloadTrigger, cacheKey, func) {
+  const fromCache = cacheGet(cacheKey);
+  if (fromCache) {
+    return fromCache;
+  } else {
+    const generation = acquireCacheGeneration();
+    try {
+      const res = await getCachedPromise(reloadTrigger, cacheKey, func);
+      if (getCacheGenerationForKey(cacheKey) > generation) {
+        return cacheGet(cacheKey) || res;
+      } else {
+        cacheSet(cacheKey, res, reloadTrigger, generation);
+        return res;
+      }
+    } catch (err) {
+      console.error('Error when using cached promise', err);
+      cacheClean(cacheKey);
+      const res = await func();
+      cacheSet(cacheKey, res, reloadTrigger, generation);
+      return res;
+    }
+  }
+}
+
+export async function subscribeCacheChange(reloadTrigger, cacheKey, reloadHandler) {
+  for (const item of getAsArray(reloadTrigger)) {
+    if (!subscriptionsByReloadTrigger[item]) {
+      subscriptionsByReloadTrigger[item] = [];
+    }
+    subscriptionsByReloadTrigger[item].push(reloadHandler);
+  }
+}
+
+export async function unsubscribeCacheChange(reloadTrigger, cacheKey, reloadHandler) {
+  for (const item of getAsArray(reloadTrigger)) {
+    if (subscriptionsByReloadTrigger[item]) {
+      subscriptionsByReloadTrigger[item] = subscriptionsByReloadTrigger[item].filter(x => x != reloadHandler);
+    }
+    if (subscriptionsByReloadTrigger[item].length == 0) {
+      delete subscriptionsByReloadTrigger[item];
+    }
+  }
+}
+
+function dispatchCacheChange(reloadTrigger) {
+  cacheClean(reloadTrigger);
+
+  for (const item of getAsArray(reloadTrigger)) {
+    if (subscriptionsByReloadTrigger[item]) {
+      for (const handler of subscriptionsByReloadTrigger[item]) {
+        handler();
+      }
+    }
+  }
+}
+
+apiOn('changed-cache', reloadTrigger => dispatchCacheChange(reloadTrigger));

packages/web/src/utility/metadataLoaders.ts

@@ -1,7 +1,6 @@
 import _ from 'lodash';
-import { cacheGet, cacheSet, getCachedPromise } from './cache';
+import { loadCachedValue, subscribeCacheChange, unsubscribeCacheChange } from './cache';
 import stableStringify from 'json-stable-stringify';
-import { cacheClean } from './cache';
 import getAsArray from './getAsArray';
 import { DatabaseInfo } from 'dbgate-types';
 import { derived } from 'svelte/store';
@@ -123,7 +122,7 @@ const appFilesLoader = ({ folder }) => ({
 
 const usedAppsLoader = ({ conid, database }) => ({
   url: 'apps/get-used-apps',
-  params: {  },
+  params: {},
   reloadTrigger: `used-apps-changed`,
 });
 
@@ -172,11 +171,7 @@ async function getCore(loader, args) {
     return res;
   }
 
-  const fromCache = cacheGet(key);
+  const res = await loadCachedValue(reloadTrigger, key, doLoad);
-  if (fromCache) return fromCache;
-  const res = await getCachedPromise(key, doLoad);
-
-  cacheSet(key, res, reloadTrigger);
   return res;
 }
 
@@ -187,77 +182,20 @@ function useCore(loader, args) {
   return {
     subscribe: onChange => {
       async function handleReload() {
-        async function doLoad() {
+        const res = await getCore(loader, args);
-          const resp = await apiCall(url, params);
+        onChange(res);
-          const res = (transform || (x => x))(resp);
-          if (onLoaded) onLoaded(res);
-          return res;
       }
 
-        if (cacheKey) {
-          const fromCache = cacheGet(cacheKey);
-          if (fromCache) {
-            onChange(fromCache);
-          } else {
-            try {
-              const res = await getCachedPromise(cacheKey, doLoad);
-              cacheSet(cacheKey, res, reloadTrigger);
-              onChange(res);
-            } catch (err) {
-              console.error(`Error when using cached promise ${url}`, err);
-              cacheClean(cacheKey);
-              const res = await doLoad();
-              cacheSet(cacheKey, res, reloadTrigger);
-              onChange(res);
-            }
-          }
-        } else {
-          const res = await doLoad();
-          onChange(res);
-        }
-      }
-
-      // if (reloadTrigger && !socket) {
-      //   console.error('Socket not available, reloadTrigger not planned');
-      // }
       handleReload();
+
       if (reloadTrigger) {
-        for (const item of getAsArray(reloadTrigger)) {
+        subscribeCacheChange(reloadTrigger, cacheKey, handleReload);
-          apiOn(item, handleReload);
-        }
         return () => {
-          for (const item of getAsArray(reloadTrigger)) {
+          unsubscribeCacheChange(reloadTrigger, cacheKey, handleReload);
-            apiOff(item, handleReload);
-          }
         };
       }
     },
   };
-
-  // const useTrack = track => ({
-  //   subscribe: onChange => {
-  //     onChange('TRACK ' + track);
-  //     if (track) {
-  //       const handle = setInterval(() => onChange('TRACK ' + track + ';' + new Date()), 1000);
-  //       // console.log("ON", track);
-  //       const oldTrack = track;
-  //       return () => {
-  //         clearInterval(handle);
-  //         // console.log("OFF", oldTrack);
-  //       };
-  //     }
-  //   },
-  // });
-
-  // const res = useFetch({
-  //   url,
-  //   params,
-  //   reloadTrigger,
-  //   cacheKey,
-  //   transform,
-  // });
-
-  // return res;
 }
 
 /** @returns {Promise<import('dbgate-types').DatabaseInfo>} */
@@ -439,8 +377,6 @@ export function useAppFolders(args = {}) {
   return useCore(appFoldersLoader, args);
 }
 
-
-
 export function getUsedApps(args = {}) {
   return getCore(usedAppsLoader, args);
 }