Nix/src/libstore/remote-fs-accessor.cc

#include "remote-fs-accessor.hh"
#include "nar-accessor.hh"

namespace nix {

RemoteFSAccessor::RemoteFSAccessor(ref<Store> store, const Path & cacheDir)
    : store(store)
    , cacheDir(cacheDir)
{
    if (cacheDir != "")
        createDirs(cacheDir);
}

Path RemoteFSAccessor::makeCacheFile(const Path & storePath)
{
    assert(cacheDir != "");
    return fmt("%s/%s.nar", cacheDir, storePathToHash(storePath));
}

void RemoteFSAccessor::addToCache(const Path & storePath, const std::string & nar)
{
    try {
        if (cacheDir == "") return;
        /* FIXME: do this asynchronously. */
        writeFile(makeCacheFile(storePath), nar);
    } catch (...) {
        ignoreException();
    }
}

std::pair<ref<FSAccessor>, Path> RemoteFSAccessor::fetch(const Path & path_)
{
    auto path = canonPath(path_);

    auto storePath = store->toStorePath(path);
    std::string restPath = std::string(path, storePath.size());

    if (!store->isValidPath(storePath))
        throw InvalidPath(format("path '%1%' is not a valid store path") % storePath);

    auto i = nars.find(storePath);
    if (i != nars.end()) return {i->second, restPath};

    StringSink sink;

    try {
        if (cacheDir != "")
            *sink.s = nix::readFile(makeCacheFile(storePath));
    } catch (SysError &) { }

    if (sink.s->empty()) {
        store->narFromPath(storePath, sink);
        addToCache(storePath, *sink.s);
    }

    auto accessor = makeNarAccessor(sink.s);
    nars.emplace(storePath, accessor);
    return {accessor, restPath};
}

FSAccessor::Stat RemoteFSAccessor::stat(const Path & path)
{
    auto res = fetch(path);
    return res.first->stat(res.second);
}

StringSet RemoteFSAccessor::readDirectory(const Path & path)
{
    auto res = fetch(path);
    return res.first->readDirectory(res.second);
}

std::string RemoteFSAccessor::readFile(const Path & path)
{
    auto res = fetch(path);
    return res.first->readFile(res.second);
}

std::string RemoteFSAccessor::readLink(const Path & path)
{
    auto res = fetch(path);
    return res.first->readLink(res.second);
}

}