fix(KeySetCache): handle concurrent generation

Resolves #305
This commit is contained in:
rudy
2021-12-15 15:12:45 +01:00
committed by rudy-6-4
parent 68e124964c
commit 7a286ba9f9

View File

@@ -1,9 +1,13 @@
#include "zamalang/Support/KeySetCache.h"
#include "zamalang/Support/Error.h"
#include "llvm/ADT/ScopeExit.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Path.h"
#include <fstream>
#include <functional>
#include <string>
extern "C" {
#include "concrete-ffi.h"
}
@@ -150,9 +154,11 @@ llvm::Error saveKeys(KeySet &key_set, llvm::SmallString<0> &folderPath) {
err = llvm::sys::fs::rename(folderIncompletePath, folderPath);
if (err) {
llvm::sys::fs::remove_directories(folderIncompletePath);
}
if (!llvm::sys::fs::exists(folderPath)) {
return StreamStringError()
<< "Cannot rename directory \"" << folderIncompletePath << "\" \""
<< folderPath << "\": " << err.message();
<< "Cannot save directory \"" << folderPath << "\"";
}
return llvm::Error::success();
@@ -172,21 +178,49 @@ KeySetCache::tryLoadOrGenerateSave(ClientParameters &params, uint64_t seed_msb,
if (llvm::sys::fs::exists(folderPath)) {
return tryLoadKeys(params, seed_msb, seed_lsb, folderPath);
} else {
auto key_set = KeySet::generate(params, seed_msb, seed_lsb);
if (!key_set) {
return StreamStringError()
<< "Cannot generate key set: " << key_set.takeError();
}
auto savedErr = saveKeys(*(key_set.get()), folderPath);
if (savedErr) {
return StreamStringError() << "Cannot save key set: " << savedErr;
}
return key_set;
}
// Creating a lock for concurrent generation
llvm::SmallString<0> lockPath(folderPath);
lockPath.append("lock");
int FD_lock;
llvm::sys::fs::create_directories(llvm::sys::path::parent_path(lockPath));
// Open or create the lock file
auto err = llvm::sys::fs::openFile(
lockPath, FD_lock, llvm::sys::fs::CreationDisposition::CD_OpenAlways,
llvm::sys::fs::FileAccess::FA_Write, llvm::sys::fs::OpenFlags::OF_None);
if (err) {
// parent does not exists OR right issue (creation or write)
return StreamStringError()
<< "Cannot access \"" << lockPath << "\": " << err.message();
}
// The first to lock will generate while the others waits
llvm::sys::fs::lockFile(FD_lock);
auto cleanUnlock = llvm::make_scope_exit([&]() {
llvm::sys::fs::unlockFile(FD_lock);
llvm::sys::fs::remove(lockPath);
});
if (llvm::sys::fs::exists(folderPath)) {
// Others returns here
return tryLoadKeys(params, seed_msb, seed_lsb, folderPath);
}
auto key_set = KeySet::generate(params, seed_msb, seed_lsb);
if (!key_set) {
return StreamStringError()
<< "Cannot generate key set: " << key_set.takeError();
}
auto savedErr = saveKeys(*(key_set.get()), folderPath);
if (savedErr) {
return StreamStringError() << "Cannot save key set: " << savedErr;
}
return key_set;
}
} // namespace zamalang