1 files changed, 173 insertions, 0 deletions
diff --git a/third_party/nix/src/libstore/http-binary-cache-store.cc b/third_party/nix/src/libstore/http-binary-cache-store.cc
new file mode 100644
index 0000000000..779f89e68d
--- /dev/null
+++ b/third_party/nix/src/libstore/http-binary-cache-store.cc
@@ -0,0 +1,173 @@
+#include "binary-cache-store.hh"
+#include "download.hh"
+#include "globals.hh"
+#include "nar-info-disk-cache.hh"
+
+namespace nix {
+
+MakeError(UploadToHTTP, Error);
+
+class HttpBinaryCacheStore : public BinaryCacheStore
+{
+private:
+
+    Path cacheUri;
+
+    struct State
+    {
+        bool enabled = true;
+        std::chrono::steady_clock::time_point disabledUntil;
+    };
+
+    Sync<State> _state;
+
+public:
+
+    HttpBinaryCacheStore(
+        const Params & params, const Path & _cacheUri)
+        : BinaryCacheStore(params)
+        , cacheUri(_cacheUri)
+    {
+        if (cacheUri.back() == '/')
+            cacheUri.pop_back();
+
+        diskCache = getNarInfoDiskCache();
+    }
+
+    std::string getUri() override
+    {
+        return cacheUri;
+    }
+
+    void init() override
+    {
+        // FIXME: do this lazily?
+        if (!diskCache->cacheExists(cacheUri, wantMassQuery_, priority)) {
+            try {
+                BinaryCacheStore::init();
+            } catch (UploadToHTTP &) {
+                throw Error("'%s' does not appear to be a binary cache", cacheUri);
+            }
+            diskCache->createCache(cacheUri, storeDir, wantMassQuery_, priority);
+        }
+    }
+
+protected:
+
+    void maybeDisable()
+    {
+        auto state(_state.lock());
+        if (state->enabled && settings.tryFallback) {
+            int t = 60;
+            printError("disabling binary cache '%s' for %s seconds", getUri(), t);
+            state->enabled = false;
+            state->disabledUntil = std::chrono::steady_clock::now() + std::chrono::seconds(t);
+        }
+    }
+
+    void checkEnabled()
+    {
+        auto state(_state.lock());
+        if (state->enabled) return;
+        if (std::chrono::steady_clock::now() > state->disabledUntil) {
+            state->enabled = true;
+            debug("re-enabling binary cache '%s'", getUri());
+            return;
+        }
+        throw SubstituterDisabled("substituter '%s' is disabled", getUri());
+    }
+
+    bool fileExists(const std::string & path) override
+    {
+        checkEnabled();
+
+        try {
+            DownloadRequest request(cacheUri + "/" + path);
+            request.head = true;
+            getDownloader()->download(request);
+            return true;
+        } catch (DownloadError & e) {
+            /* S3 buckets return 403 if a file doesn't exist and the
+               bucket is unlistable, so treat 403 as 404. */
+            if (e.error == Downloader::NotFound || e.error == Downloader::Forbidden)
+                return false;
+            maybeDisable();
+            throw;
+        }
+    }
+
+    void upsertFile(const std::string & path,
+        const std::string & data,
+        const std::string & mimeType) override
+    {
+        auto req = DownloadRequest(cacheUri + "/" + path);
+        req.data = std::make_shared<string>(data); // FIXME: inefficient
+        req.mimeType = mimeType;
+        try {
+            getDownloader()->download(req);
+        } catch (DownloadError & e) {
+            throw UploadToHTTP("while uploading to HTTP binary cache at '%s': %s", cacheUri, e.msg());
+        }
+    }
+
+    DownloadRequest makeRequest(const std::string & path)
+    {
+        DownloadRequest request(cacheUri + "/" + path);
+        return request;
+    }
+
+    void getFile(const std::string & path, Sink & sink) override
+    {
+        checkEnabled();
+        auto request(makeRequest(path));
+        try {
+            getDownloader()->download(std::move(request), sink);
+        } catch (DownloadError & e) {
+            if (e.error == Downloader::NotFound || e.error == Downloader::Forbidden)
+                throw NoSuchBinaryCacheFile("file '%s' does not exist in binary cache '%s'", path, getUri());
+            maybeDisable();
+            throw;
+        }
+    }
+
+    void getFile(const std::string & path,
+        Callback<std::shared_ptr<std::string>> callback) noexcept override
+    {
+        checkEnabled();
+
+        auto request(makeRequest(path));
+
+        auto callbackPtr = std::make_shared<decltype(callback)>(std::move(callback));
+
+        getDownloader()->enqueueDownload(request,
+            {[callbackPtr, this](std::future<DownloadResult> result) {
+                try {
+                    (*callbackPtr)(result.get().data);
+                } catch (DownloadError & e) {
+                    if (e.error == Downloader::NotFound || e.error == Downloader::Forbidden)
+                        return (*callbackPtr)(std::shared_ptr<std::string>());
+                    maybeDisable();
+                    callbackPtr->rethrow();
+                } catch (...) {
+                    callbackPtr->rethrow();
+                }
+            }});
+    }
+
+};
+
+static RegisterStoreImplementation regStore([](
+    const std::string & uri, const Store::Params & params)
+    -> std::shared_ptr<Store>
+{
+    if (std::string(uri, 0, 7) != "http://" &&
+        std::string(uri, 0, 8) != "https://" &&
+        (getEnv("_NIX_FORCE_HTTP_BINARY_CACHE_STORE") != "1" || std::string(uri, 0, 7) != "file://")
+        ) return 0;
+    auto store = std::make_shared<HttpBinaryCacheStore>(params, uri);
+    store->init();
+    return store;
+});
+
+}
+