feat(core): duration.toHumanString()

packages/@aws-cdk/aws-dynamodb/test/test.dynamodb.ts

@@ -1,7 +1,7 @@
 import { expect, haveResource, ResourcePart, SynthUtils } from '@aws-cdk/assert';
 import * as appscaling from '@aws-cdk/aws-applicationautoscaling';
 import * as iam from '@aws-cdk/aws-iam';
-import { App, CfnDeletionPolicy, ConstructNode, RemovalPolicy, Stack, Tag } from '@aws-cdk/core';
+import { App, CfnDeletionPolicy, ConstructNode, Duration, RemovalPolicy, Stack, Tag } from '@aws-cdk/core';
 import { Test } from 'nodeunit';
 import {
   Attribute,
@@ -1142,7 +1142,7 @@ export = {
 
       // THEN
       test.deepEqual(stack.resolve(table.metricConsumedReadCapacityUnits()), {
-        period: { amount: 5, unit: { label: 'minutes', inSeconds: 60 } },
+        period: Duration.minutes(5),
         dimensions: { TableName: { Ref: 'TableCD117FA1' } },
         namespace: 'AWS/DynamoDB',
         metricName: 'ConsumedReadCapacityUnits',
@@ -1161,7 +1161,7 @@ export = {
 
       // THEN
       test.deepEqual(stack.resolve(table.metricConsumedWriteCapacityUnits()), {
-        period: { amount: 5, unit: { label: 'minutes', inSeconds: 60 } },
+        period: Duration.minutes(5),
         dimensions: { TableName: { Ref: 'TableCD117FA1' } },
         namespace: 'AWS/DynamoDB',
         metricName: 'ConsumedWriteCapacityUnits',
@@ -1180,7 +1180,7 @@ export = {
 
       // THEN
       test.deepEqual(stack.resolve(table.metricSystemErrors()), {
-        period: { amount: 5, unit: { label: 'minutes', inSeconds: 60 } },
+        period: Duration.minutes(5),
         dimensions: { TableName: { Ref: 'TableCD117FA1' } },
         namespace: 'AWS/DynamoDB',
         metricName: 'SystemErrors',
@@ -1199,7 +1199,7 @@ export = {
 
       // THEN
       test.deepEqual(stack.resolve(table.metricUserErrors()), {
-        period: { amount: 5, unit: { label: 'minutes', inSeconds: 60 } },
+        period: Duration.minutes(5),
         dimensions: { TableName: { Ref: 'TableCD117FA1' } },
         namespace: 'AWS/DynamoDB',
         metricName: 'UserErrors',
@@ -1218,7 +1218,7 @@ export = {
 
       // THEN
       test.deepEqual(stack.resolve(table.metricConditionalCheckFailedRequests()), {
-        period: { amount: 5, unit: { label: 'minutes', inSeconds: 60 } },
+        period: Duration.minutes(5),
         dimensions: { TableName: { Ref: 'TableCD117FA1' } },
         namespace: 'AWS/DynamoDB',
         metricName: 'ConditionalCheckFailedRequests',
@@ -1237,7 +1237,7 @@ export = {
 
       // THEN
       test.deepEqual(stack.resolve(table.metricSuccessfulRequestLatency()), {
-        period: { amount: 5, unit: { label: 'minutes', inSeconds: 60 } },
+        period: Duration.minutes(5),
         dimensions: { TableName: { Ref: 'TableCD117FA1' } },
         namespace: 'AWS/DynamoDB',
         metricName: 'SuccessfulRequestLatency',

packages/@aws-cdk/core/lib/duration.ts

@@ -10,6 +10,8 @@ import { Token } from "./token";
  */
 export class Duration {
   /**
+   * Create a Duration representing an amount of milliseconds
+   *
    * @param amount the amount of Milliseconds the `Duration` will represent.
    * @returns a new `Duration` representing `amount` ms.
    */
@@ -18,6 +20,8 @@ export class Duration {
   }
 
   /**
+   * Create a Duration representing an amount of seconds
+   *
    * @param amount the amount of Seconds the `Duration` will represent.
    * @returns a new `Duration` representing `amount` Seconds.
    */
@@ -26,6 +30,8 @@ export class Duration {
   }
 
   /**
+   * Create a Duration representing an amount of minutes
+   *
    * @param amount the amount of Minutes the `Duration` will represent.
    * @returns a new `Duration` representing `amount` Minutes.
    */
@@ -34,6 +40,8 @@ export class Duration {
   }
 
   /**
+   * Create a Duration representing an amount of hours
+   *
    * @param amount the amount of Hours the `Duration` will represent.
    * @returns a new `Duration` representing `amount` Hours.
    */
@@ -42,6 +50,8 @@ export class Duration {
   }
 
   /**
+   * Create a Duration representing an amount of days
+   *
    * @param amount the amount of Days the `Duration` will represent.
    * @returns a new `Duration` representing `amount` Days.
    */
@@ -50,8 +60,9 @@ export class Duration {
   }
 
   /**
-   * Parse a period formatted according to the ISO 8601 standard (see https://www.iso.org/fr/standard/70907.html).
+   * Parse a period formatted according to the ISO 8601 standard
    *
+   * @see https://www.iso.org/fr/standard/70907.html
    * @param duration an ISO-formtted duration to be parsed.
    * @returns the parsed `Duration`.
    */
@@ -64,11 +75,11 @@ export class Duration {
     if (!days && !hours && !minutes && !seconds) {
       throw new Error(`Not a valid ISO duration: ${duration}`);
     }
-    return Duration.seconds(
-      _toInt(seconds)
-      + (_toInt(minutes) * TimeUnit.Minutes.inSeconds)
-      + (_toInt(hours) * TimeUnit.Hours.inSeconds)
-      + (_toInt(days) * TimeUnit.Days.inSeconds)
+    return Duration.millis(
+      _toInt(seconds) * TimeUnit.Seconds.inMillis
+      + (_toInt(minutes) * TimeUnit.Minutes.inMillis)
+      + (_toInt(hours) * TimeUnit.Hours.inMillis)
+      + (_toInt(days) * TimeUnit.Days.inMillis)
     );
 
     function _toInt(str: string): number {
@@ -90,44 +101,57 @@ export class Duration {
   }
 
   /**
+   * Return the total number of milliseconds in this Duration
+   *
    * @returns the value of this `Duration` expressed in Milliseconds.
    */
   public toMilliseconds(opts: TimeConversionOptions = {}): number {
     return convert(this.amount, this.unit, TimeUnit.Milliseconds, opts);
   }
 
   /**
+   * Return the total number of seconds in this Duration
+   *
    * @returns the value of this `Duration` expressed in Seconds.
    */
   public toSeconds(opts: TimeConversionOptions = {}): number {
     return convert(this.amount, this.unit, TimeUnit.Seconds, opts);
   }
 
   /**
+   * Return the total number of minutes in this Duration
+   *
    * @returns the value of this `Duration` expressed in Minutes.
    */
   public toMinutes(opts: TimeConversionOptions = {}): number {
     return convert(this.amount, this.unit, TimeUnit.Minutes, opts);
   }
 
   /**
+   * Return the total number of hours in this Duration
+   *
    * @returns the value of this `Duration` expressed in Hours.
    */
   public toHours(opts: TimeConversionOptions = {}): number {
     return convert(this.amount, this.unit, TimeUnit.Hours, opts);
   }
 
   /**
+   * Return the total number of days in this Duration
+   *
    * @returns the value of this `Duration` expressed in Days.
    */
   public toDays(opts: TimeConversionOptions = {}): number {
     return convert(this.amount, this.unit, TimeUnit.Days, opts);
   }
 
   /**
-   * @returns an ISO 8601 representation of this period (see https://www.iso.org/fr/standard/70907.html).
+   * Return an ISO 8601 representation of this period
+   *
+   * @returns a string starting with 'PT' describing the period
+   * @see https://www.iso.org/fr/standard/70907.html
    */
-  public toISOString(): string {
+  public toIsoString(): string {
     if (this.amount === 0) { return 'PT0S'; }
     switch (this.unit) {
       case TimeUnit.Seconds:
@@ -143,6 +167,52 @@ export class Duration {
     }
   }
 
+  /**
+   * Return an ISO 8601 representation of this period
+   *
+   * @returns a string starting with 'PT' describing the period
+   * @see https://www.iso.org/fr/standard/70907.html
+   * @deprecated Use `toIsoString()` instead.
+   */
+  public toISOString(): string {
+    return this.toIsoString();
+  }
+
+  /**
+   * Turn this duration into a human-readable string
+   */
+  public toHumanString(): string {
+    if (this.amount === 0) { return fmtUnit(0, this.unit); }
+    if (Token.isUnresolved(this.amount)) { return `<token> ${this.unit.label}`; }
+
+    let millis = convert(this.amount, this.unit, TimeUnit.Milliseconds, { integral: false });
+    const parts = new Array<string>();
+
+    for (const unit of [TimeUnit.Days, TimeUnit.Hours, TimeUnit.Hours, TimeUnit.Minutes, TimeUnit.Seconds]) {
+      const wholeCount = Math.floor(convert(millis, TimeUnit.Milliseconds, unit, { integral: false }));
+      if (wholeCount > 0) {
+        parts.push(fmtUnit(wholeCount, unit));
+        millis -= wholeCount * unit.inMillis;
+      }
+    }
+
+    // Remainder in millis
+    if (millis > 0) {
+      parts.push(fmtUnit(millis, TimeUnit.Milliseconds));
+    }
+
+    // 2 significant parts, that's totally enough for humans
+    return parts.slice(0, 2).join(' ');
+
+    function fmtUnit(amount: number, unit: TimeUnit) {
+      if (amount === 1) {
+        // All of the labels end in 's'
+        return `${amount} ${unit.label.substring(0, unit.label.length - 1)}`;
+      }
+      return `${amount} ${unit.label}`;
+    }
+  }
+
   /**
    * Returns a string representation of this `Duration` that is also a Token that cannot be successfully resolved. This
    * protects users against inadvertently stringifying a `Duration` object, when they should have called one of the
@@ -183,13 +253,16 @@ export interface TimeConversionOptions {
 }
 
 class TimeUnit {
-  public static readonly Milliseconds = new TimeUnit('millis', 0.001);
-  public static readonly Seconds = new TimeUnit('seconds', 1);
-  public static readonly Minutes = new TimeUnit('minutes', 60);
-  public static readonly Hours = new TimeUnit('hours', 3_600);
-  public static readonly Days = new TimeUnit('days', 86_400);
+  public static readonly Milliseconds = new TimeUnit('millis', 1);
+  public static readonly Seconds = new TimeUnit('seconds', 1_000);
+  public static readonly Minutes = new TimeUnit('minutes', 60_000);
+  public static readonly Hours = new TimeUnit('hours', 3_600_000);
+  public static readonly Days = new TimeUnit('days', 86_400_000);
 
-  private constructor(public readonly label: string, public readonly inSeconds: number) {
+  private constructor(public readonly label: string, public readonly inMillis: number) {
+    // MAX_SAFE_INTEGER is 2^53, so by representing our duration in millis (the lowest
+    // common unit) the highest duration we can represent is
+    // 2^53 / 86*10^6 ~= 104 * 10^6 days (about 100 million days).
   }
 
   public toString() {
@@ -198,8 +271,8 @@ class TimeUnit {
 }
 
 function convert(amount: number, fromUnit: TimeUnit, toUnit: TimeUnit, { integral = true }: TimeConversionOptions) {
-  if (fromUnit.inSeconds === toUnit.inSeconds) { return amount; }
-  const multiplier = fromUnit.inSeconds / toUnit.inSeconds;
+  if (fromUnit.inMillis === toUnit.inMillis) { return amount; }
+  const multiplier = fromUnit.inMillis / toUnit.inMillis;
 
   if (Token.isUnresolved(amount)) {
     throw new Error(`Unable to perform time unit conversion on un-resolved token ${amount}.`);

packages/@aws-cdk/core/package.json

@@ -57,17 +57,6 @@
       "docs-public-apis:@aws-cdk/core.ConstructNode.root",
       "docs-public-apis:@aws-cdk/core.ContextProvider.getKey",
       "docs-public-apis:@aws-cdk/core.ContextProvider.getValue",
-      "docs-public-apis:@aws-cdk/core.Duration.days",
-      "docs-public-apis:@aws-cdk/core.Duration.hours",
-      "docs-public-apis:@aws-cdk/core.Duration.millis",
-      "docs-public-apis:@aws-cdk/core.Duration.minutes",
-      "docs-public-apis:@aws-cdk/core.Duration.seconds",
-      "docs-public-apis:@aws-cdk/core.Duration.toDays",
-      "docs-public-apis:@aws-cdk/core.Duration.toHours",
-      "docs-public-apis:@aws-cdk/core.Duration.toISOString",
-      "docs-public-apis:@aws-cdk/core.Duration.toMilliseconds",
-      "docs-public-apis:@aws-cdk/core.Duration.toMinutes",
-      "docs-public-apis:@aws-cdk/core.Duration.toSeconds",
       "docs-public-apis:@aws-cdk/core.Lazy.anyValue",
       "docs-public-apis:@aws-cdk/core.Lazy.listValue",
       "docs-public-apis:@aws-cdk/core.Lazy.numberValue",

packages/@aws-cdk/core/test/test.duration.ts

@@ -1,5 +1,5 @@
 import * as nodeunit from 'nodeunit';
-import { Duration, Stack, Token } from '../lib';
+import { Duration, Lazy, Stack, Token } from '../lib';
 
 export = nodeunit.testCase({
   'negative amount'(test: nodeunit.Test) {
@@ -93,6 +93,22 @@ export = nodeunit.testCase({
     test.done();
   },
 
+  'toIsoString'(test: nodeunit.Test) {
+    test.equal(Duration.seconds(0).toIsoString(), 'PT0S');
+    test.equal(Duration.minutes(0).toIsoString(), 'PT0S');
+    test.equal(Duration.hours(0).toIsoString(), 'PT0S');
+    test.equal(Duration.days(0).toIsoString(), 'PT0S');
+
+    test.equal(Duration.seconds(5).toIsoString(), 'PT5S');
+    test.equal(Duration.minutes(5).toIsoString(), 'PT5M');
+    test.equal(Duration.hours(5).toIsoString(), 'PT5H');
+    test.equal(Duration.days(5).toIsoString(), 'PT5D');
+
+    test.equal(Duration.seconds(1 + 60 * (1 + 60 * (1 + 24))).toIsoString(), 'PT1D1H1M1S');
+
+    test.done();
+  },
+
   'parse'(test: nodeunit.Test) {
     test.equal(Duration.parse('PT0S').toSeconds(), 0);
     test.equal(Duration.parse('PT0M').toSeconds(), 0);
@@ -107,7 +123,26 @@ export = nodeunit.testCase({
     test.equal(Duration.parse('PT1D1H1M1S').toSeconds(), 1 + 60 * (1 + 60 * (1 + 24)));
 
     test.done();
-  }
+  },
+
+  'to human string'(test: nodeunit.Test) {
+    test.equal(Duration.minutes(0).toHumanString(), '0 minutes');
+    test.equal(Duration.minutes(Lazy.numberValue({ produce: () => 5 })).toHumanString(), '<token> minutes');
+
+    test.equal(Duration.minutes(10).toHumanString(), '10 minutes');
+    test.equal(Duration.minutes(1).toHumanString(), '1 minute');
+
+    test.equal(Duration.minutes(62).toHumanString(), '1 hour 2 minutes');
+
+    test.equal(Duration.seconds(3666).toHumanString(), '1 hour 1 minute');
+
+    test.equal(Duration.millis(3000).toHumanString(), '3 seconds');
+    test.equal(Duration.millis(3666).toHumanString(), '3 seconds 666 millis');
+
+    test.equal(Duration.millis(3.6).toHumanString(), '3.6 millis');
+
+    test.done();
+  },
 });
 
 function floatEqual(test: nodeunit.Test, actual: number, expected: number) {