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* In normaliseFState(), wrap registration of the output paths and the

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normal form in a single transaction to ensure that if we crash,
  either everything is registered or nothing is.  This is for
  recoverability: unregistered paths in the store can be deleted
  arbitrarily, while registered paths can only be deleted by running
  the garbage collector.
This commit is contained in:
Eelco Dolstra 2003-08-01 15:41:47 +00:00
parent d99d04e644
commit c95b4ad290
6 changed files with 44 additions and 28 deletions
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39
src/normalise.cc
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@ -8,19 +8,10 @@
#include "globals.hh"
void registerSuccessor(const FSId & id1, const FSId & id2)
void registerSuccessor(const Transaction & txn,
const FSId & id1, const FSId & id2)
{
Transaction txn(nixDB);
nixDB.setString(txn, dbSuccessors, id1, id2);
txn.commit();
}
static FSId storeSuccessor(const FSId & id1, ATerm sc)
{
FSId id2 = writeTerm(sc, "-s-" + (string) id1);
registerSuccessor(id1, id2);
return id2;
}
@ -153,7 +144,7 @@ FSId normaliseFState(FSId id, FSIdSet pending)
expandId(i->second, i->first, "/", pending);
} catch (Error & e) {
debug(format("fast build failed for `%1%': %2%")
% i->first % e.what());
% i->first % e.what());
fastBuild = false;
break;
}
@ -175,8 +166,8 @@ FSId normaliseFState(FSId id, FSIdSet pending)
} else
msg(lvlChatty, format("fast build succesful"));
/* Check whether the output paths were created, and register each
one. */
/* Check whether the output paths were created, and grep each
output path to determine what other paths it references. */
FSIdSet used;
for (OutPaths::iterator i = outPaths.begin();
i != outPaths.end(); i++)
@ -184,7 +175,6 @@ FSId normaliseFState(FSId id, FSIdSet pending)
string path = i->first;
if (!pathExists(path))
throw Error(format("path `%1%' does not exist") % path);
registerPath(path, i->second);
fs.slice.roots.push_back(i->second);
Strings refs = filterReferences(path, refPaths);
@ -224,10 +214,27 @@ FSId normaliseFState(FSId id, FSIdSet pending)
}
}
/* Write the normal form. This does not have to occur in the
transaction below because writing terms is idem-potent. */
fs.type = FState::fsSlice;
ATerm nf = unparseFState(fs);
msg(lvlVomit, format("normal form: %1%") % printTerm(nf));
return storeSuccessor(id, nf);
FSId idNF = writeTerm(nf, "-s-" + (string) id);
/* Register each outpat path, and register the normal form. This
is wrapped in one database transaction to ensure that if we
crash, either everything is registered or nothing is. This is
for recoverability: unregistered paths in the store can be
deleted arbitrarily, while registered paths can only be deleted
by running the garbage collector. */
Transaction txn(nixDB);
for (OutPaths::iterator i = outPaths.begin();
i != outPaths.end(); i++)
registerPath(txn, i->first, i->second);
registerSuccessor(txn, id, idNF);
txn.commit();
return idNF;
}