Add a helper in BackupStoreAccounts to get a write lock on an account.

Use it in two places to simplify code (not in BackupStoreContext yet,
because that wants to communicate with HK process as well).

1 files changed, 36 insertions, 4 deletions

diff --git a/lib/backupstore/BackupStoreAccounts.cpp b/lib/backupstore/BackupStoreAccounts.cpp
index b7ef13ab..18500fc1 100644
--- a/lib/backupstore/BackupStoreAccounts.cpp
+++ b/lib/backupstore/BackupStoreAccounts.cpp
@@ -11,14 +11,16 @@
 
 #include <stdio.h>
 
-#include "BoxPortsAndFiles.h"
 #include "BackupStoreAccounts.h"
 #include "BackupStoreAccountDatabase.h"
+#include "BackupStoreConstants.h"
+#include "BackupStoreDirectory.h"
+#include "BackupStoreException.h"
+#include "BackupStoreInfo.h"
 #include "BackupStoreRefCountDatabase.h"
+#include "BoxPortsAndFiles.h"
 #include "RaidFileWrite.h"
-#include "BackupStoreInfo.h"
-#include "BackupStoreDirectory.h"
-#include "BackupStoreConstants.h"
+#include "StoreStructure.h"
 #include "UnixUser.h"
 
 #include "MemLeakFindOn.h"
@@ -168,4 +170,34 @@ bool BackupStoreAccounts::AccountExists(int32_t ID)
 	return mrDatabase.EntryExists(ID);
 }
 
+void BackupStoreAccounts::LockAccount(int32_t ID, NamedLock& rNamedLock)
+{
+	const BackupStoreAccountDatabase::Entry &en(mrDatabase.GetEntry(ID));
+	std::string rootDir = MakeAccountRootDir(ID, en.GetDiscSet());
+	int discSet = en.GetDiscSet();
+
+	std::string writeLockFilename;
+	StoreStructure::MakeWriteLockFilename(rootDir, discSet, writeLockFilename);
+
+	bool gotLock = false;
+	int triesLeft = 8;
+	do
+	{
+		gotLock = rNamedLock.TryAndGetLock(writeLockFilename,
+			0600 /* restrictive file permissions */);
+		
+		if(!gotLock)
+		{
+			--triesLeft;
+			::sleep(1);
+		}
+	}
+	while (!gotLock && triesLeft > 0);
 
+	if (!gotLock)
+	{
+		THROW_EXCEPTION_MESSAGE(BackupStoreException,
+			CouldNotLockStoreAccount, "Failed to get exclusive "
+			"lock on account " << ID);
+	}
+}