Add caching for -attributes endpoints

Author: gabrielfeo

gradle.properties

@@ -1,3 +1,4 @@
+org.gradle.jvmargs=-Xmx5g
 org.gradle.caching=true
 # Must be later than 2022.1
 gradle.enterprise.version=2022.4

src/main/kotlin/com/gabrielfeo/gradle/enterprise/api/Api.kt

@@ -5,7 +5,6 @@ package com.gabrielfeo.gradle.enterprise.api
 import com.gabrielfeo.gradle.enterprise.api.auth.HttpBearerAuth
 import com.gabrielfeo.gradle.enterprise.api.infrastructure.Serializer
 import okhttp3.OkHttpClient
-import okhttp3.logging.HttpLoggingInterceptor
 import retrofit2.Retrofit
 import retrofit2.converter.moshi.MoshiConverterFactory
 import retrofit2.converter.scalars.ScalarsConverterFactory
@@ -14,19 +13,25 @@ import kotlin.time.Duration.Companion.seconds
 
 var baseUrl: () -> String = { requireBaseUrl() }
 var accessToken: () -> String = { requireToken() }
+
 var maxConcurrentRequests = 30
+var maxCacheSize = 500_000_000L
+
+val cacheablePaths: MutableList<Regex> = mutableListOf(
+    """.*/api/builds/[\d\w]+/(?:gradle|maven)-attributes""".toRegex(),
+)
 
 val okHttpClient: OkHttpClient by lazy {
     OkHttpClient.Builder()
+        .cache(cache)
         .addInterceptor(HttpBearerAuth("bearer", accessToken()))
-        .addInterceptor(HttpLoggingInterceptor())
+        .addInterceptor(CacheHitLoggingInterceptor())
+        .addNetworkInterceptor(CacheEnforcingInterceptor(cacheablePaths))
         .build()
         .apply {
             dispatcher.maxRequests = maxConcurrentRequests
             dispatcher.maxRequestsPerHost = maxConcurrentRequests
-            if (_debugLoggingEnabled) {
-                logRequestCountEvery(2.seconds)
-            }
+            startRequestCountLogging(this, period = 2.seconds)
         }
 }
 

src/main/kotlin/com/gabrielfeo/gradle/enterprise/api/Caching.kt

@@ -0,0 +1,39 @@
+package com.gabrielfeo.gradle.enterprise.api
+
+import okhttp3.*
+import okhttp3.HttpUrl.Companion.toHttpUrl
+import java.io.File
+import kotlin.time.Duration.Companion.days
+
+internal val cache: Cache = run {
+    val host = baseUrl().toHttpUrl().host
+    val tempDir = System.getProperty("java.io.tmpdir")
+    Cache(
+        directory = File(tempDir, "gradle-enterprise-api-cache-$host"),
+        maxSize = maxCacheSize,
+    )
+}
+
+internal class CacheEnforcingInterceptor(
+    private val cacheablePaths: List<Regex>,
+) : Interceptor {
+
+    private val maxAge = 365.days.inWholeMilliseconds
+
+    override fun intercept(chain: Interceptor.Chain): Response {
+        val request = chain.request()
+        if (!isCacheable(request)) {
+            return chain.proceed(request)
+        }
+        val response = chain.proceed(request)
+        return response.newBuilder()
+            .header("cache-control", "max-age=$maxAge")
+            .removeHeader("pragma")
+            .removeHeader("expires")
+            .removeHeader("vary")
+            .build()
+    }
+
+    private fun isCacheable(request: Request) =
+        cacheablePaths.any { it.matches(request.url.toString()) }
+}

src/main/kotlin/com/gabrielfeo/gradle/enterprise/api/DebugLogging.kt

@@ -4,20 +4,45 @@ import kotlinx.coroutines.DelicateCoroutinesApi
 import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
+import okhttp3.Interceptor
 import okhttp3.OkHttpClient
+import okhttp3.Response
 import java.util.logging.Level.INFO
 import java.util.logging.Logger
 import kotlin.time.Duration
 
 @Suppress("ObjectPropertyName")
 var _debugLoggingEnabled = System.getenv("GRADLE_ENTERPRISE_API_DEBUG_LOGGING").toBoolean()
 
+internal class CacheHitLoggingInterceptor(
+    private val logger: Logger = Logger.getGlobal(),
+) : Interceptor {
+
+    override fun intercept(chain: Interceptor.Chain): Response {
+        if (!_debugLoggingEnabled) {
+            return chain.proceed(chain.request())
+        }
+        val url = chain.request().url
+        val response = chain.proceed(chain.request())
+        val wasHit = with(response) { cacheResponse != null && networkResponse == null }
+        val hitOrMiss = if (wasHit) "hit" else "miss"
+        logger.log(INFO, "Cache $hitOrMiss: $url")
+        return response
+    }
+}
+
 @OptIn(DelicateCoroutinesApi::class)
-internal fun OkHttpClient.logRequestCountEvery(period: Duration) {
+internal fun startRequestCountLogging(
+    client: OkHttpClient,
+    period: Duration,
+    logger: Logger = Logger.getGlobal(),
+) {
+    if (!_debugLoggingEnabled) {
+        return
+    }
     GlobalScope.launch {
-        val logger = Logger.getGlobal()
-        while (!dispatcher.executorService.isShutdown) {
-            val count = dispatcher.runningCallsCount()
+        while (!client.dispatcher.executorService.isShutdown) {
+            val count = client.dispatcher.runningCallsCount()
             logger.log(INFO, "$count requests running")
             delay(period)
         }