wip: implement the simplest version of compilation job cache

v-next/hardhat/src/internal/builtin-plugins/solidity/build-system/build-system.ts

@@ -44,6 +44,7 @@ import {
   getContractArtifact,
   getDuplicatedContractNamesDeclarationFile,
 } from "./artifacts.js";
+import { Cache } from "./cache.js";
 import { CompilationJobImplementation } from "./compilation-job.js";
 import { downloadConfiguredCompilers, getCompiler } from "./compiler/index.js";
 import { buildDependencyGraph } from "./dependency-graph-building.js";
@@ -67,11 +68,16 @@ export interface SolidityBuildSystemOptions {
 
 export class SolidityBuildSystemImplementation implements SolidityBuildSystem {
   readonly #options: SolidityBuildSystemOptions;
+  readonly #compilerOutputCache: Cache;
   readonly #defaultConcurrenty = Math.max(os.cpus().length - 1, 1);
   #downloadedCompilers = false;
 
   constructor(options: SolidityBuildSystemOptions) {
     this.#options = options;
+    this.#compilerOutputCache = new Cache(
+      options.cachePath,
+      "hardhat:core:solidity:build-system:compiler-output",
+    );
   }
 
   public async getRootFilePaths(): Promise<string[]> {
@@ -112,8 +118,6 @@ export class SolidityBuildSystemImplementation implements SolidityBuildSystem {
 
     const compilationJobs = [...new Set(compilationJobsPerFile.values())];
 
-    // TODO: Filter the compilation jobs based on the cache
-
     const results: CompilerOutput[] = await pMap(
       compilationJobs,
       (compilationJob) => this.runCompilationJob(compilationJob),
@@ -312,6 +316,17 @@ export class SolidityBuildSystemImplementation implements SolidityBuildSystem {
     compilationJob: CompilationJob,
     options?: RunCompilationJobOptions,
   ): Promise<CompilerOutput> {
+    if (options?.force !== true) {
+      const buildId = compilationJob.getBuildId();
+
+      const cachedCompilerOutput =
+        await this.#compilerOutputCache.getJson<CompilerOutput>(buildId);
+      if (cachedCompilerOutput !== undefined) {
+        log(`Using cached compiler output for build ${buildId}`);
+        return cachedCompilerOutput;
+      }
+    }
+
     await this.#downloadConfiguredCompilers(options?.quiet);
 
     let numberOfFiles = 0;
@@ -332,7 +347,19 @@ export class SolidityBuildSystemImplementation implements SolidityBuildSystem {
       "The long version of the compiler should match the long version of the compilation job",
     );
 
-    return compiler.compile(compilationJob.getSolcInput());
+    const compilerOutput = await compiler.compile(
+      compilationJob.getSolcInput(),
+    );
+
+    if (options?.force !== true) {
+      const buildId = compilationJob.getBuildId();
+
+      if (!this.#hasCompilationErrors(compilerOutput)) {
+        await this.#compilerOutputCache.setJson(buildId, compilerOutput);
+      }
+    }
+
+    return compilerOutput;
   }
 
   public async remapCompilerError(

v-next/hardhat/src/internal/builtin-plugins/solidity/build-system/cache.ts

@@ -0,0 +1,32 @@
+import path from "node:path";
+
+import {
+  exists,
+  readJsonFile,
+  writeJsonFile,
+} from "@ignored/hardhat-vnext-utils/fs";
+
+export class Cache {
+  readonly #basePath: string;
+  readonly #namespace: string;
+
+  constructor(basePath: string, namespace: string) {
+    this.#basePath = basePath;
+    this.#namespace = namespace;
+
+    console.log(`Using cache at ${this.#basePath}`);
+  }
+
+  public async getJson<T>(key: string): Promise<T | undefined> {
+    const filePath = path.join(this.#basePath, this.#namespace, key);
+    if (await exists(filePath)) {
+      return readJsonFile<T>(filePath);
+    }
+    return undefined;
+  }
+
+  public async setJson<T>(key: string, value: T): Promise<void> {
+    const filePath = path.join(this.#basePath, this.#namespace, key);
+    await writeJsonFile(filePath, value);
+  }
+}

v-next/hardhat/src/types/solidity/build-system.ts

@@ -62,6 +62,12 @@ export type GetCompilationJobsOptions = Omit<
  * The options of the `runCompilationJob` method.
  */
 export interface RunCompilationJobOptions {
+  /**
+   * If `true`, this option foces the build system to rerun the compilation job,
+   * even if its output is cached.
+   */
+  force?: boolean;
+
   /**
    * If `true`, the compilation process doesn't print any output.
    */
@@ -265,7 +271,7 @@ export interface SolidityBuildSystem {
    * This method should only be used after a complete build has succeeded, as
    * it relies on the build system to have generated all the necessary artifact
    * files.
-   
+
    * @param rootFilePaths All the root files of the project.
    */
   cleanupArtifacts(rootFilePaths: string[]): Promise<void>;