Improved performance for large download queues

src/app/core/services/download.service.ts

@@ -11,7 +11,19 @@ export class DownloadService {
   private downloads: DownloadProgress[] = []
 
   constructor(private electronService: ElectronService) {
-    process.setMaxListeners(100)
+    this.electronService.receiveIPC('download-updated', result => {
+      // Update <this.downloads> with result
+      const thisDownloadIndex = this.downloads.findIndex(download => download.versionID == result.versionID)
+      if (result.type == 'cancel') {
+        this.downloads = this.downloads.filter(download => download.versionID != result.versionID)
+      } else if (thisDownloadIndex == -1) {
+        this.downloads.push(result)
+      } else {
+        this.downloads[thisDownloadIndex] = result
+      }
+
+      this.downloadUpdatedEmitter.emit(result)
+    })
   }
 
   get downloadCount() {
@@ -32,19 +44,6 @@ export class DownloadService {
 
   addDownload(versionID: number, newDownload: NewDownload) {
     if (!this.downloads.find(download => download.versionID == versionID)) { // Don't download something twice
-      this.electronService.receiveIPC('download-updated', result => {
-        // Update <this.downloads> with result
-        const thisDownloadIndex = this.downloads.findIndex(download => download.versionID == result.versionID)
-        if (result.type == 'cancel') {
-          this.downloads = this.downloads.filter(download => download.versionID != versionID)
-        } else if (thisDownloadIndex == -1) {
-          this.downloads.push(result)
-        } else {
-          this.downloads[thisDownloadIndex] = result
-        }
-
-        this.downloadUpdatedEmitter.emit(result)
-      })
       this.electronService.sendIPC('download', { action: 'add', versionID, data: newDownload })
     }
   }

src/app/core/services/selection.service.ts

@@ -17,7 +17,7 @@ export class SelectionService {
   private searchResults: SongResult[] = []
 
   private selectAllChangedEmitter = new EventEmitter<boolean>()
-  private selectionChangedEmitter = new EventEmitter<SelectionEvent>()
+  private selectionChangedCallbacks: { [songID: number]: (selection: boolean) => void } = {}
 
   private allSelected = false
   private selections: { [songID: number]: boolean | undefined } = {}
@@ -32,7 +32,9 @@ export class SelectionService {
 
     searchService.onNewSearch((results) => {
       this.searchResults = results
-      this.deselectAll()
+      this.selectionChangedCallbacks = {}
+      this.selections = {}
+      this.selectAllChangedEmitter.emit(false)
     })
   }
 
@@ -49,11 +51,7 @@ export class SelectionService {
    * (note: only one emitter can be registered per `songID`)
    */
   onSelectionChanged(songID: number, callback: (selection: boolean) => void) {
-    this.selectionChangedEmitter.subscribe((selection: SelectionEvent) => {
-      if (selection.songID == songID) {
-        callback(selection.selected)
-      }
-    })
+    this.selectionChangedCallbacks[songID] = callback
   }
 
 
@@ -78,14 +76,14 @@ export class SelectionService {
   deselectSong(songID: number) {
     if (this.selections[songID]) {
       this.selections[songID] = false
-      this.selectionChangedEmitter.emit({ songID, selected: false })
+      this.selectionChangedCallbacks[songID](false)
     }
   }
 
   selectSong(songID: number) {
     if (!this.selections[songID]) {
       this.selections[songID] = true
-      this.selectionChangedEmitter.emit({ songID, selected: true })
+      this.selectionChangedCallbacks[songID](true)
     }
   }
 }