Function Purity Analysis for Memoization

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Memoization techniques face challenges in identifying and optimizing functions with side effects, as existing methods struggle to classify functions as pure or impure, leading to inefficiencies in caching and performance gains.

Innovation Solution

A method is developed to analyze function purity by examining performance history, using control flow graphs and side effect classification, allowing for memoization of functions with consistent and predictable side effects, even if they are not purely pure, by traversing the control flow graph and applying statistical confidence criteria.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If memoization is applied to functions with side effects, then performance improvement is achieved through caching, but function purity is compromised leading to incorrect results

Engineering Contradiction:
Improveperformance improvementVSAvoidfunction purity
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent changes the parameter of function classification from strict purity to statistical purity by introducing a confidence threshold. Functions are evaluated based on whether they exceed a predetermined statistical confidence threshold for pure behavior, allowing impure functions with consistent side effects to be classified as pure for memoization purposes.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies partial memoization by selectively caching only functions that meet the statistical purity threshold while excluding those that fail the threshold. This partial action allows performance optimization for suitable functions without incorrectly caching functions with non-trivial side effects.

Inventive Principle:
Principle #16Partial or excessive action

2Reliability

If strict purity analysis is performed, then function reliability is maintained, but many functions are excluded from memoization reducing performance gains

Engineering Contradiction:
Improvefunction purityVSAvoidmemoization coverage
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent relaxes the purity parameter from binary (pure/impure) to statistical (confidence threshold). By changing the classification criterion to whether a function exceeds a predetermined statistical confidence threshold, more functions qualify for memoization while maintaining acceptable reliability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces dynamic evaluation of function purity through statistical analysis of function execution history. Instead of static analysis, the system dynamically determines purity based on observed behavior patterns and confidence thresholds, allowing adaptive classification.

Inventive Principle:
Principle #15Dynamics

3Loss of time

If functions with side effects are memoized, then computational overhead is reduced, but incorrect results may be returned

Engineering Contradiction:
Improvecomputational overheadVSAvoidresult accuracy
Core Design Contradiction:
Loss of timeVSMeasurement precision

Solution Approach 1:

The patent changes the accuracy parameter by introducing statistical confidence thresholds. Results are considered accurate enough for caching when the function's pure behavior exceeds a predetermined statistical confidence threshold, balancing result accuracy with performance optimization.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback through statistical analysis of function execution history. The system continuously monitors function behavior and uses this feedback to determine whether a function meets the purity threshold for memoization, adjusting classification based on observed performance patterns.

Inventive Principle:
Principle #23Feedback

4Measurement precision

If statistical confidence analysis is performed, then function classification accuracy is improved, but analysis time and complexity increase

Engineering Contradiction:
Improvepurity classification accuracyVSAvoidanalysis time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies partial analysis by performing statistical confidence evaluation only for functions that are candidates for memoization, rather than analyzing all functions exhaustively. This partial action reduces overall analysis time while maintaining high classification accuracy for relevant functions.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent performs preliminary statistical analysis during function execution to build confidence data, which is then used for classification decisions. This preliminary action allows accurate classification without requiring complex real-time analysis during every function call.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS8839204B2Determination of function purity for memoization
Publication Date: 2014.09.16 MICROSOFT TECHNOLOGY LICENSING LLC
  • US8839204B2 patent drawing
  • US8839204B2 patent drawing
  • US8839204B2 patent drawing

AI summary

The purity of a function may be determined after examining the performance history of a function and analyzing the conditions under which the function behaves as pure. In some cases, a function may be classified as pure when any side effects are de minimis or are otherwise considered trivial. A control flow graph may also be traversed to identify conditions in which a side effect may occur as well as to classify the side effects as trivial or non-trivial. The function purity may be used to identify functions for memoization. In some embodiments, the purity analysis may be performed by a remote server and communicated to a client device, where the client device may memoize the function.