nix-super/src/libstore/build-result.hh

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#pragma once
///@file
#include "realisation.hh"
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#include "derived-path.hh"
#include "comparator.hh"
#include <string>
#include <chrono>
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#include <optional>
namespace nix {
struct BuildResult
{
/**
* @note This is directly used in the nix-store --serve protocol.
* That means we need to worry about compatability across versions.
* Therefore, don't remove status codes, and only add new status
* codes at the end of the list.
*/
enum Status {
Built = 0,
Substituted,
AlreadyValid,
PermanentFailure,
InputRejected,
OutputRejected,
/// possibly transient
TransientFailure,
/// no longer used
CachedFailure,
TimedOut,
MiscFailure,
DependencyFailed,
LogLimitExceeded,
NotDeterministic,
ResolvesToAlreadyValid,
NoSubstituters,
} status = MiscFailure;
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/**
* Information about the error if the build failed.
*
* @todo This should be an entire ErrorInfo object, not just a
* string, for richer information.
*/
std::string errorMsg;
std::string toString() const {
auto strStatus = [&]() {
switch (status) {
case Built: return "Built";
case Substituted: return "Substituted";
case AlreadyValid: return "AlreadyValid";
case PermanentFailure: return "PermanentFailure";
case InputRejected: return "InputRejected";
case OutputRejected: return "OutputRejected";
case TransientFailure: return "TransientFailure";
case CachedFailure: return "CachedFailure";
case TimedOut: return "TimedOut";
case MiscFailure: return "MiscFailure";
case DependencyFailed: return "DependencyFailed";
case LogLimitExceeded: return "LogLimitExceeded";
case NotDeterministic: return "NotDeterministic";
case ResolvesToAlreadyValid: return "ResolvesToAlreadyValid";
case NoSubstituters: return "NoSubstituters";
default: return "Unknown";
};
}();
return strStatus + ((errorMsg == "") ? "" : " : " + errorMsg);
}
/**
* How many times this build was performed.
*/
unsigned int timesBuilt = 0;
/**
* If timesBuilt > 1, whether some builds did not produce the same
* result. (Note that 'isNonDeterministic = false' does not mean
* the build is deterministic, just that we don't have evidence of
* non-determinism.)
*/
bool isNonDeterministic = false;
/**
* For derivations, a mapping from the names of the wanted outputs
* to actual paths.
*/
SingleDrvOutputs builtOutputs;
/**
* The start/stop times of the build (or one of the rounds, if it
* was repeated).
*/
time_t startTime = 0, stopTime = 0;
/**
* User and system CPU time the build took.
*/
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std::optional<std::chrono::microseconds> cpuUser, cpuSystem;
DECLARE_CMP(BuildResult);
bool success()
{
return status == Built || status == Substituted || status == AlreadyValid || status == ResolvesToAlreadyValid;
}
void rethrow()
{
throw Error("%s", errorMsg);
}
};
Make `KeyedBuildResult`, `BuildResult` like before, and fix bug another way In https://github.com/NixOS/nix/pull/6311#discussion_r834863823, I realized since derivation goals' wanted outputs can "grow" due to overlapping dependencies (See `DerivationGoal::addWantedOutputs`, called by `Worker::makeDerivationGoalCommon`), the previous bug fix had an unfortunate side effect of causing more pointless rebuilds. In paticular, we have this situation: 1. Goal made from `DerivedPath::Built { foo, {a} }`. 2. Goal gives on on substituting, starts building. 3. Goal made from `DerivedPath::Built { foo, {b} }`, in fact is just modified original goal. 4. Though the goal had gotten as far as building, so all outputs were going to be produced, `addWantedOutputs` no longer knows that and so the goal is flagged to be restarted. This might sound far-fetched with input-addressed drvs, where we usually basically have all our goals "planned out" before we start doing anything, but with CA derivation goals and especially RFC 92, where *drv resolution* means goals are created after some building is completed, it is more likely to happen. So the first thing to do was restore the clearing of `wantedOutputs` we used to do, and then filter the outputs in `buildPathsWithResults` to only get the ones we care about. But fix also has its own side effect in that the `DerivedPath` in the `BuildResult` in `DerivationGoal` cannot be trusted; it is merely the *first* `DerivedPath` for which this goal was originally created. To remedy this, I made `BuildResult` be like it was before, and instead made `KeyedBuildResult` be a subclass wit the path. Only `buildPathsWithResults` returns `KeyedBuildResult`s, everything else just becomes like it was before, where the "key" is unambiguous from context. I think separating the "primary key" field(s) from the other fields is good practical in general anyways. (I would like to do the same thing for `ValidPathInfo`.) Among other things, it allows constructions like `std::map<Key, ThingWithKey>` where doesn't contain duplicate keys and just precludes the possibility of those duplicate keys being out of sync. We might leverage the above someday to overload `buildPathsWithResults` to take a *set* of return a *map* per the above. ----- Unfortunately, we need to avoid C++20 strictness on designated initializers. (BTW https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2287r1.html this offers some new syntax for this use-case. Hopefully this will be adopted and we can eventually use it.) No having that yet, maybe it would be better to not make `KeyedBuildResult` a subclass to just avoid this. Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
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/**
* A `BuildResult` together with its "primary key".
*/
struct KeyedBuildResult : BuildResult
{
/**
* The derivation we built or the store path we substituted.
*/
DerivedPath path;
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// Hack to work around a gcc "may be used uninitialized" warning.
KeyedBuildResult(BuildResult res, DerivedPath path)
: BuildResult(std::move(res)), path(std::move(path))
{ }
Make `KeyedBuildResult`, `BuildResult` like before, and fix bug another way In https://github.com/NixOS/nix/pull/6311#discussion_r834863823, I realized since derivation goals' wanted outputs can "grow" due to overlapping dependencies (See `DerivationGoal::addWantedOutputs`, called by `Worker::makeDerivationGoalCommon`), the previous bug fix had an unfortunate side effect of causing more pointless rebuilds. In paticular, we have this situation: 1. Goal made from `DerivedPath::Built { foo, {a} }`. 2. Goal gives on on substituting, starts building. 3. Goal made from `DerivedPath::Built { foo, {b} }`, in fact is just modified original goal. 4. Though the goal had gotten as far as building, so all outputs were going to be produced, `addWantedOutputs` no longer knows that and so the goal is flagged to be restarted. This might sound far-fetched with input-addressed drvs, where we usually basically have all our goals "planned out" before we start doing anything, but with CA derivation goals and especially RFC 92, where *drv resolution* means goals are created after some building is completed, it is more likely to happen. So the first thing to do was restore the clearing of `wantedOutputs` we used to do, and then filter the outputs in `buildPathsWithResults` to only get the ones we care about. But fix also has its own side effect in that the `DerivedPath` in the `BuildResult` in `DerivationGoal` cannot be trusted; it is merely the *first* `DerivedPath` for which this goal was originally created. To remedy this, I made `BuildResult` be like it was before, and instead made `KeyedBuildResult` be a subclass wit the path. Only `buildPathsWithResults` returns `KeyedBuildResult`s, everything else just becomes like it was before, where the "key" is unambiguous from context. I think separating the "primary key" field(s) from the other fields is good practical in general anyways. (I would like to do the same thing for `ValidPathInfo`.) Among other things, it allows constructions like `std::map<Key, ThingWithKey>` where doesn't contain duplicate keys and just precludes the possibility of those duplicate keys being out of sync. We might leverage the above someday to overload `buildPathsWithResults` to take a *set* of return a *map* per the above. ----- Unfortunately, we need to avoid C++20 strictness on designated initializers. (BTW https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2287r1.html this offers some new syntax for this use-case. Hopefully this will be adopted and we can eventually use it.) No having that yet, maybe it would be better to not make `KeyedBuildResult` a subclass to just avoid this. Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
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};
}