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import { IImage } from '../types';
import { uuidv4 } from '../utilities';
type AdditionalDetails = {
imageId?: string;
volumeId?: string;
};
type RequestDetailsInterface = {
requestFn: () => Promise<IImage | void>;
type: RequestType;
additionalDetails: AdditionalDetails;
};
type RequestPool = {
[name in RequestType]: { [key: number]: RequestDetailsInterface[] };
};
/**
* RequestPool manager class is a base class that manages the request pools.
* It is used imageRetrievalPoolManager, and imageLoadPoolManager to retrieve and load images.
* Previously requestPoolManager was used to manage the retrieval and loading and decoding
* of the images in a way that new requests were sent after the image was both loaded and decoded
* which was not performant since it was waiting for the image to be loaded and decoded before
* sending the next request which is a network request and can be done in parallel.
* Now, we use separate imageRetrievalPoolManager and imageLoadPoolManager
* to improve performance and both are extending the RequestPoolManager class which
* is a basic queueing pool.
*
* A new requestPool can be created by instantiating a new RequestPoolManager class.
*
* ```javascript
* const requestPoolManager = new RequestPoolManager()
* ```
*
* ## ImageLoadPoolManager
*
* You can use the imageLoadPoolManager to load images, by providing a `requestFn`
* that returns a promise for the image. You can provide a `type` to specify the type of
* request (interaction, thumbnail, prefetch), and you can provide additional details
* that will be passed to the requestFn. Below is an example of a requestFn that loads
* an image from an imageId:
*
* ```javascript
*
* const priority = -5
* const requestType = RequestType.Interaction
* const additionalDetails = { imageId }
* const options = {
* targetBuffer: {
* type: 'Float32Array',
* offset: null,
* length: null,
* },
* preScale: {
* enabled: true,
* },
* }
*
* imageLoadPoolManager.addRequest(
* loadAndCacheImage(imageId, options).then(() => { // set on viewport}),
* requestType,
* additionalDetails,
* priority
* )
* ```
* ### ImageRetrievalPoolManager
* You don't need to directly use the imageRetrievalPoolManager to load images
* since the imageLoadPoolManager will automatically use it for retrieval. However,
* maximum number of concurrent requests can be set by calling `setMaxConcurrentRequests`.
*/
class RequestPoolManager {
private id: string;
private awake: boolean;
private requestPool: RequestPool;
private numRequests = {
interaction: 0,
thumbnail: 0,
prefetch: 0,
};
/* maximum number of requests of each type. */
public maxNumRequests: {
interaction: number;
thumbnail: number;
prefetch: number;
};
/* A public property that is used to set the delay between requests. */
public grabDelay: number;
private timeoutHandle: number;
/**
* By default a request pool containing three priority groups, one for each
* of the request types, is created. Maximum number of requests of each type
* is set to 6.
*/
constructor(id?: string) {
this.id = id ? id : uuidv4();
this.requestPool = {
interaction: { 0: [] },
thumbnail: { 0: [] },
prefetch: { 0: [] },
};
this.grabDelay = 5;
this.awake = false;
this.numRequests = {
interaction: 0,
thumbnail: 0,
prefetch: 0,
};
this.maxNumRequests = {
interaction: 6,
thumbnail: 6,
prefetch: 5,
};
}
/**
* This function sets the maximum number of requests for a given request type.
* @param type - The type of request you want to set the max number
* of requests for it can be either of interaction, prefetch, or thumbnail.
* @param maxNumRequests - The maximum number of requests that can be
* made at a time.
*/
public setMaxSimultaneousRequests(
type: RequestType,
maxNumRequests: number
): void {
this.maxNumRequests[type] = maxNumRequests;
}
/**
* It returns the maximum number of requests of a given type that can be made
* @param type - The type of request.
* @returns The maximum number of requests of a given type.
*/
public getMaxSimultaneousRequests(type: RequestType): number {
return this.maxNumRequests[type];
}
/**
* Stops further fetching of the requests, all the ongoing requests will still
* be retrieved
*/
public destroy(): void {
if (this.timeoutHandle) {
window.clearTimeout(this.timeoutHandle);
}
}
/**
* Adds the requests to the pool of requests.
*
* @param requestFn - A function that returns a promise which resolves in the image
* @param type - Priority category, it can be either of interaction, prefetch,
* or thumbnail.
* @param additionalDetails - Additional details that requests can contain.
* For instance the volumeId for the volume requests
* @param priority - Priority number for each category of requests. Its default
* value is priority 0. The lower the priority number, the higher the priority number
*
*/
public addRequest(
requestFn: () => Promise<IImage | void>,
type: RequestType,
additionalDetails: Record<string, unknown>,
priority = 0
): void {
// Describe the request
const requestDetails: RequestDetailsInterface = {
requestFn,
type,
additionalDetails,
};
// Check if the priority group exists on the request type
if (this.requestPool[type][priority] === undefined) {
this.requestPool[type][priority] = [];
}
// Adding the request to the correct priority group of the request type
this.requestPool[type][priority].push(requestDetails);
// Wake up
Eif (!this.awake) {
this.awake = true;
this.startGrabbing();
} else if (type === RequestType.Interaction) {
// Todo: this is a hack for interaction right now, we should separate
// the grabbing from the adding requests
this.startGrabbing();
}
}
/**
* Filter the requestPoolManager's pool of request based on the result of
* provided filter function. The provided filter function needs to return false or true
*
* @param filterFunction - The filter function for filtering of the requests to keep
*/
public filterRequests(
filterFunction: (requestDetails: RequestDetailsInterface) => boolean
): void {
Object.keys(this.requestPool).forEach((type: string) => {
const requestType = this.requestPool[type];
Object.keys(requestType).forEach((priority) => {
requestType[priority] = requestType[priority].filter(
(requestDetails: RequestDetailsInterface) => {
return filterFunction(requestDetails);
}
);
});
});
}
/**
* Clears the requests specific to the provided type. For instance, the
* pool of requests of type 'interaction' can be cleared via this function.
*
*
* @param type - category of the request (either interaction, prefetch or thumbnail)
*/
public clearRequestStack(type: string): void {
if (!this.requestPool[type]) {
throw new Error(`No category for the type ${type} found`);
}
this.requestPool[type] = { 0: [] };
}
private sendRequests(type) {
const requestsToSend = this.maxNumRequests[type] - this.numRequests[type];
for (let i = 0; i < requestsToSend; i++) {
const requestDetails = this.getNextRequest(type);
if (requestDetails === null) {
return false;
} else Eif (requestDetails) {
this.numRequests[type]++;
this.awake = true;
requestDetails.requestFn().finally(() => {
this.numRequests[type]--;
this.startAgain();
});
}
}
return true;
}
private getNextRequest(type): RequestDetailsInterface | null {
const interactionPriorities = this.getSortedPriorityGroups(type);
for (const priority of interactionPriorities) {
Eif (this.requestPool[type][priority].length) {
return this.requestPool[type][priority].shift();
}
}
return null;
}
protected startGrabbing(): void {
const hasRemainingInteractionRequests = this.sendRequests(
RequestType.Interaction
);
const hasRemainingThumbnailRequests = this.sendRequests(
RequestType.Thumbnail
);
const hasRemainingPrefetchRequests = this.sendRequests(
RequestType.Prefetch
);
Eif (
!hasRemainingInteractionRequests &&
!hasRemainingThumbnailRequests &&
!hasRemainingPrefetchRequests
) {
this.awake = false;
}
}
protected startAgain(): void {
Eif (!this.awake) {
return;
}
if (this.grabDelay !== undefined) {
this.timeoutHandle = window.setTimeout(() => {
this.startGrabbing();
}, this.grabDelay);
} else {
this.startGrabbing();
}
}
protected getSortedPriorityGroups(type: string): Array<number> {
const priorities = Object.keys(this.requestPool[type])
.map(Number)
.filter((priority) => this.requestPool[type][priority].length)
.sort();
return priorities;
}
/**
* Returns the request pool containing different categories, their priority and
* the added request details.
*
* @returns the request pool which contains different categories, their priority and
* the added request details
*/
getRequestPool(): RequestPool {
return this.requestPool;
}
}
const requestPoolManager = new RequestPoolManager();
export { RequestPoolManager };
export default requestPoolManager;
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