Build Graph Caching via Segmentation and Hash Keys
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Solution Overview
Problem
Software build processes are inefficient due to the need to reconstruct entire build graphs after changes, which can be time-consuming and resource-intensive, especially when dealing with large numbers of source code files and dependencies.
Innovation Solution
Implementing a build graph caching system that stores and retrieves portions of the build graph unaffected by changes, using a key-value store and API routines like StoreBuildGraph and FetchBuildGraph, which utilize fingerprints and hash combinations to efficiently cache and retrieve dependency relationships.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire build graph is reconstructed after changes, then the build system ensures complete accuracy, but the build time increases significantly
Solution Approach 1:
The build graph is divided into multiple independent portions or subgraphs. Each portion can be cached and reused separately. When changes occur, only the affected portions need to be reconstructed while other portions can be retrieved from cache, thereby maintaining accuracy where needed while reducing overall reconstruction time.
Solution Approach 2:
The build graph portions are pre-computed and stored in a cache before they are needed. This allows the build system to quickly retrieve previously computed portions without reconstructing them, while still ensuring accuracy by validating or reconstructing only the changed portions when necessary.
2Productivity
If build graph caching is implemented, then build speed improves, but system complexity increases
Solution Approach 1:
Instead of implementing a complex intelligent caching system, the solution creates simple copies of build graph portions and stores them in a cache. The cache stores serialized representations of graph portions that can be quickly copied and reused. This approach prioritizes simplicity and speed over complex optimization algorithms.
Solution Approach 2:
The build graph is segmented into independent portions that can be cached separately. Each portion is identified by a unique key (such as a hash of the input specification). This segmentation allows the caching system to be simple and modular, where each cached portion is independently managed without requiring complex interdependencies tracking.
3Speed
If the build graph is cached in memory, then retrieval speed improves, but memory usage increases
Solution Approach 1:
The build graph is divided into smaller portions that are cached separately in memory. Each portion is stored with a unique key. This segmentation allows the system to cache only the portions that are frequently reused, rather than caching the entire graph, thereby optimizing memory usage while maintaining fast retrieval for the most beneficial portions.
Solution Approach 2:
The cached build graph portions are stored as serialized data structures that can be quickly created and discarded. The cache uses a key-value store where values are serialized graph portions. These cached objects are inexpensive to store and retrieve, and can be easily replaced or evicted from memory when needed, treating them as disposable short-living objects that provide quick temporary access.
Data Source
AI summary
Software build solutions are tailored to cache a build graph. The build graph is a dependency graph used to guide processes performed during a software build. Build graph caching provides faster builds after changes are made to source code files, allowing the retrieval from cache previously constructed build graph content unaffected by the change. The build graph cache includes a key-value store with an API providing StoreBuildGraph and FetchBuildGraph routines. Keys include fingerprints (hashes) of graph input parameter values, such as specification file paths, enumerated directories, and environment variables. Fingerprints may be combined by concatenation and further hashing. The API may be build-language agnostic. Pseudocode for cache store and fetch routines, and examples of their operation, are disclosed.