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#pragma once
#include "types.hh"
#include "pathlocks.hh"
#include <time.h>
namespace nix {
struct Generation
{
int number;
Path path;
time_t creationTime;
Generation()
{
number = -1;
}
operator bool() const
{
return number != -1;
}
};
typedef list<Generation> Generations;
/* Returns the list of currently present generations for the specified
profile, sorted by generation number. */
Generations findGenerations(Path profile, int & curGen);
Path createGeneration(Path profile, Path outPath, bool lazy);
void deleteGeneration(const Path & profile, unsigned int gen);
void switchLink(Path link, Path target);
/* Ensure exclusive access to a profile. Any command that modifies
the profile first acquires this lock. */
void lockProfile(PathLocks & lock, const Path & profile);
/* Optimistic locking is used by long-running operations like `nix-env
-i'. Instead of acquiring the exclusive lock for the entire
duration of the operation, we just perform the operation
optimistically (without an exclusive lock), and check at the end
whether the profile changed while we were busy (i.e., the symlink
target changed). If so, the operation is restarted. Restarting is
generally cheap, since the build results are still in the Nix
store. Most of the time, only the user environment has to be
rebuilt. */
string optimisticLockProfile(const Path & profile);
}
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