fix: correct stale timeout, allow setting minimum retry interval (#290)

Author: AlCalzone

README.md

@@ -92,9 +92,10 @@ const db = new DB("/path/to/file", { lockfile: { /* lockfile options */ } });
 | Option | Default | Description |
 |-----------------|---------|-------------|
 | `directory` | - | Change where the lockfile is created, e.g. to put the lockfile into a `tmpfs`. By default the lockfile is created in the same directory as the DB file. If the directory does not exist, it will be created when opening the DB. |
-| `staleMs` | `10000` | Duration after which the lock is considered stale. Minimum: `5000` |
+| `staleMs` | `10000` | Duration after which the lock is considered stale. Minimum: `2000` |
 | `updateMs` | `staleMs/2` | The interval in which the lockfile's `mtime` will be updated. Range: `1000 ... staleMs/2` |
 | `retries` | `0` | How often to retry acquiring a lock before giving up. The retries progressively wait longer with an exponential backoff strategy. |
+| `retryMinTimeoutMs` | `updateMs/2` or `1000` | The start interval used for retries. Minimum: `100` |
 
 
 ### Copying and compressing the database
@@ -149,6 +150,10 @@ The file will be overwritten if it exists. The 2nd options argument can be used
 	Placeholder for next release:
 	### __WORK IN PROGRESS__
 -->
+### __WORK IN PROGRESS__
+* Allow setting minimum retry timeout
+* Correct minimum value for the lockfile's stale timeout
+
 ### 2.5.0 (2022-02-13)
 * Add the ability to control the lockfile's stale/update timeouts and retrying acquiring a lock
 

src/lib/db.test.ts

@@ -134,12 +134,12 @@ describe("lib/db", () => {
 		});
 
 		describe("validates lockfile options", () => {
-			it("staleMs < 5000", () => {
+			it("staleMs < 2000", () => {
 				expect(
 					() =>
 						new JsonlDB("foo", {
 							lockfile: {
-								staleMs: 2500,
+								staleMs: 1999,
 							},
 						}),
 				).toThrowError("staleMs");
@@ -190,6 +190,17 @@ describe("lib/db", () => {
 				).toThrowError("retries");
 			});
 
+			it("retryMinTimeoutMs < 100", () => {
+				expect(
+					() =>
+						new JsonlDB("foo", {
+							lockfile: {
+								retryMinTimeoutMs: 99,
+							},
+						}),
+				).toThrowError("retryMinTimeoutMs");
+			});
+
 			it("lockfileDirectory and lockfile.directory both present", () => {
 				expect(
 					() =>

src/lib/db.ts

@@ -85,6 +85,8 @@ export interface JsonlDBOptions<V> {
 		 * Range: [0...10]. Default: 0
 		 */
 		retries?: number;
+		/** The start interval used for retries. Default: updateMs/2 */
+		retryMinTimeoutMs?: number;
 	}>;
 
 	/**
@@ -227,9 +229,10 @@ export class JsonlDB<V extends unknown = unknown> {
 				retries,
 				staleMs = 10000,
 				updateMs = staleMs / 2,
+				retryMinTimeoutMs,
 			} = options.lockfile;
-			if (staleMs < 5000) {
-				throw new Error("staleMs must be >= 5000");
+			if (staleMs < 2000) {
+				throw new Error("staleMs must be >= 2000");
 			}
 			if (updateMs < 1000) {
 				throw new Error("updateMs must be >= 1000");
@@ -243,6 +246,9 @@ export class JsonlDB<V extends unknown = unknown> {
 			if (retries != undefined && retries > 10) {
 				throw new Error("retries must be <= 10");
 			}
+			if (retryMinTimeoutMs != undefined && retryMinTimeoutMs < 100) {
+				throw new Error("retryMinTimeoutMs must be >= 100");
+			}
 			if (
 				options.lockfileDirectory != undefined &&
 				directory != undefined
@@ -309,6 +315,9 @@ export class JsonlDB<V extends unknown = unknown> {
 		let retryOptions: lockfile.LockOptions["retries"];
 		if (this.options.lockfile?.retries) {
 			retryOptions = {
+				minTimeout:
+					this.options.lockfile.retryMinTimeoutMs ??
+					(this.options.lockfile.updateMs ?? 2000) / 2,
 				retries: this.options.lockfile.retries,
 				factor: 1.25,
 			};