mpesajs
Version:
A Node.js SDK for seamless integration with M-Pesa payment gateway, providing easy-to-use methods for handling transactions, payments, and API interactions
170 lines • 6.94 kB
JavaScript
;
var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
function adopt(value) { return value instanceof P ? value : new P(function (resolve) { resolve(value); }); }
return new (P || (P = Promise))(function (resolve, reject) {
function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
function step(result) { result.done ? resolve(result.value) : adopt(result.value).then(fulfilled, rejected); }
step((generator = generator.apply(thisArg, _arguments || [])).next());
});
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.RateLimiter = void 0;
const axios_1 = require("axios");
const env_1 = require("./env");
/**
* Gets configuration from environment variables with fallbacks
* Parses string values from environment variables into appropriate types
*/
function getConfigFromEnv() {
return {
retryConfig: {
maxRetries: parseInt((0, env_1.getEnvVar)('MPESAJS_MAX_RETRIES', '3'), 10),
initialDelayMs: parseInt((0, env_1.getEnvVar)('MPESAJS_INITIAL_DELAY_MS', '1000'), 10),
maxDelayMs: parseInt((0, env_1.getEnvVar)('MPESAJS_MAX_DELAY_MS', '10000'), 10),
backoffFactor: parseInt((0, env_1.getEnvVar)('MPESAJS_BACKOFF_FACTOR', '2'), 10)
},
rateLimitConfig: {
maxConcurrent: parseInt((0, env_1.getEnvVar)('MPESAJS_MAX_CONCURRENT', '1000'), 10),
timeWindowMs: parseInt((0, env_1.getEnvVar)('MPESAJS_TIME_WINDOW_MS', '60000'), 10)
}
};
}
/**
* RateLimiter class implements rate limiting and retry logic for API requests
* Uses the Singleton pattern to ensure only one instance exists
*/
class RateLimiter {
/**
* Private constructor to prevent direct instantiation
* Initializes default configurations for retry and rate limiting
*/
constructor() {
this.queue = []; // Queue of pending requests
this.activeRequests = 0; // Current number of executing requests
this.requestTimestamps = []; // Timestamps of recent requests
const config = getConfigFromEnv();
this.retryConfig = config.retryConfig;
this.rateLimitConfig = config.rateLimitConfig;
}
/**
* Gets the singleton instance of RateLimiter
* Creates the instance if it doesn't exist
*/
static getInstance() {
if (!RateLimiter.instance) {
RateLimiter.instance = new RateLimiter();
}
return RateLimiter.instance;
}
/**
* Updates the retry configuration
* Allows partial updates while maintaining existing values
*/
setRetryConfig(config) {
this.retryConfig = Object.assign(Object.assign({}, this.retryConfig), config);
}
/**
* Updates the rate limit configuration
* Allows partial updates while maintaining existing values
*/
setRateLimitConfig(config) {
this.rateLimitConfig = Object.assign(Object.assign({}, this.rateLimitConfig), config);
}
/**
* Creates a promise that resolves after the specified delay
* Used for implementing delays between retries
*/
delay(ms) {
return __awaiter(this, void 0, void 0, function* () {
return new Promise(resolve => setTimeout(resolve, ms));
});
}
/**
* Calculates the delay time for the next retry attempt using exponential backoff
* Includes random jitter to prevent thundering herd problem
*/
calculateBackoff(attempt) {
const delay = Math.min(this.retryConfig.initialDelayMs * Math.pow(this.retryConfig.backoffFactor, attempt), this.retryConfig.maxDelayMs);
// Add 25% random jitter to prevent all retries happening simultaneously
return delay * (0.75 + Math.random() * 0.5);
}
/**
* Determines if an error should trigger a retry attempt
* Retries on network errors and specific HTTP status codes
*/
shouldRetry(error) {
var _a;
if (error instanceof axios_1.AxiosError) {
const status = (_a = error.response) === null || _a === void 0 ? void 0 : _a.status;
return !status || // Network error (no status)
status === 429 || // Too Many Requests
status === 503 || // Service Unavailable
status === 504 || // Gateway Timeout
(status >= 500 && status < 600); // Any other server error
}
return false;
}
/**
* Executes an operation with automatic retries on failure
* Implements exponential backoff between retry attempts
*/
executeWithRetry(operation_1) {
return __awaiter(this, arguments, void 0, function* (operation, attempt = 0) {
try {
return yield operation();
}
catch (error) {
if (attempt < this.retryConfig.maxRetries && this.shouldRetry(error)) {
const backoffDelay = this.calculateBackoff(attempt);
yield this.delay(backoffDelay);
return this.executeWithRetry(operation, attempt + 1);
}
throw error;
}
});
}
/**
* Removes timestamps older than the configured time window
* Helps maintain accurate count of recent requests
*/
cleanupOldTimestamps() {
const now = Date.now();
this.requestTimestamps = this.requestTimestamps.filter(timestamp => now - timestamp < this.rateLimitConfig.timeWindowMs);
}
/**
* Waits until a request slot becomes available
* Ensures we don't exceed the configured rate limits
*/
waitForAvailableSlot() {
return __awaiter(this, void 0, void 0, function* () {
while (true) {
this.cleanupOldTimestamps();
if (this.activeRequests < this.rateLimitConfig.maxConcurrent &&
this.requestTimestamps.length < this.rateLimitConfig.maxConcurrent) {
return;
}
yield this.delay(100); // Check again after 100ms
}
});
}
/**
* Main method to execute an operation with rate limiting and retry logic
* Ensures operations don't exceed rate limits and handles retries on failure
*/
execute(operation) {
return __awaiter(this, void 0, void 0, function* () {
yield this.waitForAvailableSlot();
this.activeRequests++;
this.requestTimestamps.push(Date.now());
try {
return yield this.executeWithRetry(operation);
}
finally {
this.activeRequests--;
}
});
}
}
exports.RateLimiter = RateLimiter;
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