From 338a08dc019f9fdf9cf5e4d732dc42720c7711e6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Zbigniew=20Zag=C3=B3rski?= <zbigniew@cartodb.com>
Date: Thu, 28 Nov 2024 15:45:48 +0100
Subject: [PATCH] source: enable control of cache behavior for source and query
 APIs

---
 CHANGELOG.md                       |  4 +++
 src/api/query.ts                   |  2 ++
 src/api/request-with-parameters.ts | 42 +++++++++++++++++++++++++++---
 src/sources/base-source.ts         |  3 ++-
 src/sources/types.ts               | 18 +++++++++++++
 5 files changed, 64 insertions(+), 5 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5450ff2..7414b67 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # CHANGELOG
 
+## Not released
+
+- add cache control mechanism for sources and query APIs
+
 ## 0.3
 
 ### 0.3.0
diff --git a/src/api/query.ts b/src/api/query.ts
index 3678038..b21b1b8 100644
--- a/src/api/query.ts
+++ b/src/api/query.ts
@@ -23,6 +23,7 @@ export const query = async function (
     apiBaseUrl = SOURCE_DEFAULTS.apiBaseUrl,
     clientId = SOURCE_DEFAULTS.clientId,
     maxLengthURL = SOURCE_DEFAULTS.maxLengthURL,
+    localCache,
     connectionName,
     sqlQuery,
     queryParameters,
@@ -52,5 +53,6 @@ export const query = async function (
     headers,
     errorContext,
     maxLengthURL,
+    localCache,
   });
 };
diff --git a/src/api/request-with-parameters.ts b/src/api/request-with-parameters.ts
index 0cffe1a..1ae4514 100644
--- a/src/api/request-with-parameters.ts
+++ b/src/api/request-with-parameters.ts
@@ -7,13 +7,14 @@ import {CartoAPIError, APIErrorContext} from './carto-api-error';
 import {V3_MINOR_VERSION} from '../constants-internal';
 import {DEFAULT_MAX_LENGTH_URL} from '../constants-internal';
 import {getClient} from '../client';
+import {LocalCacheOptions} from '../sources/types';
 
 const DEFAULT_HEADERS = {
   Accept: 'application/json',
   'Content-Type': 'application/json',
 };
 
-const REQUEST_CACHE = new Map<string, Promise<unknown>>();
+const DEFAULT_REQUEST_CACHE = new Map<string, Promise<unknown>>();
 
 export async function requestWithParameters<T = any>({
   baseUrl,
@@ -21,12 +22,14 @@ export async function requestWithParameters<T = any>({
   headers: customHeaders = {},
   errorContext,
   maxLengthURL = DEFAULT_MAX_LENGTH_URL,
+  localCache,
 }: {
   baseUrl: string;
   parameters?: Record<string, unknown>;
   headers?: Record<string, string>;
   errorContext: APIErrorContext;
   maxLengthURL?: number;
+  localCache?: LocalCacheOptions;
 }): Promise<T> {
   // Parameters added to all requests issued with `requestWithParameters()`.
   // These parameters override parameters already in the base URL, but not
@@ -41,7 +44,14 @@ export async function requestWithParameters<T = any>({
 
   baseUrl = excludeURLParameters(baseUrl, Object.keys(parameters));
   const key = createCacheKey(baseUrl, parameters, customHeaders);
-  if (REQUEST_CACHE.has(key)) {
+
+  const {
+    cache: REQUEST_CACHE,
+    canReadCache,
+    canStoreInCache,
+  } = getCacheSettings(localCache, customHeaders);
+
+  if (canReadCache && REQUEST_CACHE.has(key)) {
     return REQUEST_CACHE.get(key) as Promise<T>;
   }
 
@@ -73,14 +83,38 @@ export async function requestWithParameters<T = any>({
       return json;
     })
     .catch((error: Error) => {
-      REQUEST_CACHE.delete(key);
+      if (canStoreInCache) {
+        REQUEST_CACHE.delete(key);
+      }
       throw new CartoAPIError(error, errorContext, response, responseJson);
     });
 
-  REQUEST_CACHE.set(key, jsonPromise);
+  if (canStoreInCache) {
+    REQUEST_CACHE.set(key, jsonPromise);
+  }
   return jsonPromise;
 }
 
+function getCacheSettings(
+  localCache: LocalCacheOptions | undefined,
+  headers: Record<string, string>
+) {
+  const cacheControl = headers['Cache-Control'];
+  const canReadCache = localCache
+    ? localCache.canReadCache
+    : !cacheControl?.includes('no-cache');
+  const canStoreInCache = localCache
+    ? localCache.canStoreInCache
+    : !cacheControl?.includes('no-store');
+  const cache = localCache?.cache || DEFAULT_REQUEST_CACHE;
+
+  return {
+    cache,
+    canReadCache,
+    canStoreInCache,
+  };
+}
+
 function createCacheKey(
   baseUrl: string,
   parameters: Record<string, unknown>,
diff --git a/src/sources/base-source.ts b/src/sources/base-source.ts
index 3b2f530..380208a 100644
--- a/src/sources/base-source.ts
+++ b/src/sources/base-source.ts
@@ -45,7 +45,7 @@ export async function baseSource<UrlParameters extends Record<string, unknown>>(
     }
   }
   const baseUrl = buildSourceUrl(mergedOptions);
-  const {clientId, maxLengthURL, format} = mergedOptions;
+  const {clientId, maxLengthURL, format, localCache} = mergedOptions;
   const headers = {
     Authorization: `Bearer ${options.accessToken}`,
     ...options.headers,
@@ -65,6 +65,7 @@ export async function baseSource<UrlParameters extends Record<string, unknown>>(
       headers,
       errorContext,
       maxLengthURL,
+      localCache,
     });
 
   const dataUrl = mapInstantiation[format].url[0];
diff --git a/src/sources/types.ts b/src/sources/types.ts
index b039d18..af58e81 100644
--- a/src/sources/types.ts
+++ b/src/sources/types.ts
@@ -47,6 +47,24 @@ export type SourceOptionalOptions = {
    * @default {@link DEFAULT_MAX_LENGTH_URL}
    */
   maxLengthURL?: number;
+
+  /**
+   * Local cache options.
+   *  * `canReadCache`: If `true`, the source will try to read from the local memory cache.
+   *  * `canStoreInCache`: If `true`, the source will store the response in the local memory cache.
+   *  * `cache`: A map of promises that are used to store the responses.
+   *
+   * If not provided, source will try to detect `CacheControl: no-cache or no-store` headers in the response and disable respective caching modes.
+   *
+   * By default, local in-memory caching is enabled
+   */
+  localCache?: LocalCacheOptions;
+};
+
+export type LocalCacheOptions = {
+  canReadCache?: boolean;
+  canStoreInCache?: boolean;
+  cache?: Map<string, Promise<unknown>>;
 };
 
 export type SourceOptions = SourceRequiredOptions &