Add detailed logging of BackupFileSystem locks

This logging is categorised, so it can be enabled with fine-tuning using the -L
command-line option.

lib/backupstore/BackupFileSystem.cpp

@@ -56,6 +56,8 @@
 
 #include "MemLeakFindOn.h"
 
+const FileSystemCategory BackupFileSystem::LOCKING("Locking");
+
 void BackupFileSystem::GetLock(int max_tries)
 {
 	if(HaveLock())
@@ -82,11 +84,36 @@ void BackupFileSystem::GetLock(int max_tries)
 				((i < max_tries - 1) || max_tries == KEEP_TRYING_FOREVER))
 			{
 				// Sleep a bit, and try again, as long as we have retries left.
+
+				if(i == 0)
+				{
+					BOX_LOG_CATEGORY(Log::INFO, LOCKING, "Failed to lock "
+						"account " << GetAccountIdentifier() << ", "
+						"still trying...");
+				}
+				else if(i == 30)
+				{
+					BOX_LOG_CATEGORY(Log::WARNING, LOCKING, "Failed to lock "
+						"account " << GetAccountIdentifier() << " for "
+						"30 seconds, still trying...");
+				}
+
 				ShortSleep(MilliSecondsToBoxTime(1000), true);
 				// Will try again
 			}
+			else if(EXCEPTION_IS_TYPE(e, BackupStoreException,
+				CouldNotLockStoreAccount))
+			{
+				BOX_LOG_CATEGORY(Log::INFO, LOCKING, "Failed to lock account " <<
+					GetAccountIdentifier() << " after " << (i + 1) << " "
+					"attempts, giving up");
+				throw;
+			}
 			else
 			{
+				BOX_LOG_CATEGORY(Log::INFO, LOCKING, "Failed to lock account " <<
+					GetAccountIdentifier() << " " "with unexpected error: " <<
+					e.what());
 				throw;
 			}
 		}
@@ -100,6 +127,12 @@ void BackupFileSystem::GetLock(int max_tries)
 
 void BackupFileSystem::ReleaseLock()
 {
+	if(HaveLock())
+	{
+		BOX_LOG_CATEGORY(Log::TRACE, LOCKING, "Releasing lock on account " <<
+			GetAccountIdentifier());
+	}
+
 	mapBackupStoreInfo.reset();
 
 	if(mapPotentialRefCountDatabase.get())

lib/backupstore/BackupFileSystem.h

@@ -26,6 +26,15 @@ class BackupStoreInfo;
 class Configuration;
 class IOStream;
 
+class FileSystemCategory : public Log::Category
+{
+	public:
+		FileSystemCategory(const std::string& name)
+		: Log::Category(std::string("FileSystem/") + name)
+		{ }
+};
+
+
 // --------------------------------------------------------------------------
 //
 // Class
@@ -151,6 +160,8 @@ class BackupFileSystem
 		return mapPermanentRefCountDatabase.get();
 	}
 
+	static const FileSystemCategory LOCKING;
+
 protected:
 	virtual void TryGetLock() = 0;
 	virtual std::auto_ptr<BackupStoreInfo> GetBackupStoreInfoInternal(bool ReadOnly) = 0;