[GitHub] [flink] KarmaGYZ commented on a change in pull request #9760: [FLINK-13982][runtime] Implement memory calculation logics

[GitBox <gi...@apache.org>]

KarmaGYZ commented on a change in pull request #9760: [FLINK-13982][runtime] Implement memory calculation logics
URL: https://github.com/apache/flink/pull/9760#discussion_r332811245
 
 

 ##########
 File path: flink-core/src/main/java/org/apache/flink/configuration/MemorySize.java
 ##########
 @@ -115,6 +116,28 @@ public String toString() {
 		return bytes + " bytes";
 	}
 
+	// ------------------------------------------------------------------------
+	//  Calculations
+	// ------------------------------------------------------------------------
+
+	public MemorySize add(MemorySize that) {
+		return new MemorySize(Math.addExact(this.bytes, that.bytes));
+	}
+
+	public MemorySize subtract(MemorySize that) {
+		return new MemorySize(Math.subtractExact(this.bytes, that.bytes));
+	}
+
+	public MemorySize multiply(double multiplier) {
+		checkArgument(multiplier >= 0, "multiplier must be >= 0");
+
+		BigDecimal product = BigDecimal.valueOf(this.bytes).multiply(BigDecimal.valueOf(multiplier));
+		if (product.longValue() > Long.MAX_VALUE) {
+			throw new ArithmeticException("long overflow");
+		}
 
 Review comment:
   `BigDecimal::longValue` guarantee that its return value less than `Long.MAX_VALUE` and if the resulting is too big to fit in a `long`, only the low-order 64 bits are returned. So this check is useless, `BigDecimal::compareTo` could be a valid way to compare.

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