From f870bd44522d195199987b0e073d495eed060495 Mon Sep 17 00:00:00 2001
From: Julian Andres Klode <julian.klode@canonical.com>
Date: Wed, 5 Feb 2025 20:11:35 +0100
Subject: solver3: Defer version selection where possible

If a dependency can be satisfied by all versions of a package,
add the package to the clause instead of the version object.

This works only if there are no providers for the package: Providers
are quite hard to enumerate over and make sure that all versions of
a package satisfy the provider dependency.

Implement arbitrary selection between packages and versions for
the CompareProviders class: We pick the best version for each package
and then pit them against each other.
---
 doc/examples/configure-index | 1 +
 1 file changed, 1 insertion(+)

(limited to 'doc')

diff --git a/doc/examples/configure-index b/doc/examples/configure-index
index ba51a9881..1573eaa8b 100644
--- a/doc/examples/configure-index
+++ b/doc/examples/configure-index
@@ -698,6 +698,7 @@ apt::list-cleanup "<BOOL>";
 apt::authentication::trustcdrom "<BOOL>";
 apt::solver::strict-pinning "<BOOL>";
 apt::solver::enqueue-common-dependencies "<BOOL>";
+apt::solver::defer-version-selection "<BOOL>";
 apt::solver::upgrade "<BOOL>";
 apt::solver::remove "<BOOL>";
 apt::solver::removemanual "<BOOL>";
-- 
cgit v1.2.3-70-g09d2


From a9587b39ea6776b1d1324288786176102f65cee5 Mon Sep 17 00:00:00 2001
From: Julian Andres Klode <julian.klode@canonical.com>
Date: Mon, 10 Feb 2025 19:56:16 +0100
Subject: solver3: Implement a timeout, default 10s

A SAT solver can run more or less forever, but that's not a good
user experience.
---
 apt-pkg/solver3.cc           | 8 +++++++-
 apt-pkg/solver3.h            | 5 +++++
 doc/examples/configure-index | 1 +
 3 files changed, 13 insertions(+), 1 deletion(-)

(limited to 'doc')

diff --git a/apt-pkg/solver3.cc b/apt-pkg/solver3.cc
index b4a69d844..d363cdee7 100644
--- a/apt-pkg/solver3.cc
+++ b/apt-pkg/solver3.cc
@@ -32,8 +32,9 @@
 #include <apt-pkg/solver3.h>
 #include <apt-pkg/version.h>
 
-#include <algorithm>
 #include <cassert>
+#include <chrono>
+#include <ctime>
 #include <sstream>
 
 // FIXME: Helpers stolen from DepCache, please give them back.
@@ -740,6 +741,10 @@ bool APT::Solver::Pop()
       for (std::string msg; _error->PopMessage(msg);)
 	 std::cerr << "Branch failed: " << msg << std::endl;
 
+   time_t now = time(nullptr);
+   if (now - startTime >= Timeout)
+      return _error->Error("Solver timed out.");
+
    _error->RevertToStack();
 
    assert(choices.back() < solved.size());
@@ -834,6 +839,7 @@ void APT::Solver::RescoreWorkIfNeeded()
 
 bool APT::Solver::Solve()
 {
+   startTime = time(nullptr);
    while (true)
    {
       while (not Propagate())
diff --git a/apt-pkg/solver3.h b/apt-pkg/solver3.h
index 34da03ea0..da75179d5 100644
--- a/apt-pkg/solver3.h
+++ b/apt-pkg/solver3.h
@@ -213,6 +213,9 @@ class Solver
    // This is an index into the solved vector.
    std::vector<depth_type> choices{};
 
+   // \brief The time we called Solve()
+   time_t startTime;
+
    /// Various configuration options
    // \brief Debug level
    int debug{_config->FindI("Debug::APT::Solver")};
@@ -232,6 +235,8 @@ class Solver
    bool FixPolicyBroken{_config->FindB("APT::Get::Fix-Policy-Broken")};
    // \brief If set, we use strict pinning.
    bool DeferVersionSelection{_config->FindB("APT::Solver::Defer-Version-Selection", true)};
+   // \brief If set, we use strict pinning.
+   int Timeout{_config->FindI("APT::Solver::Timeout", 10)};
 
    // \brief Discover a variable, translating the underlying dependencies to the SAT presentation
    //
diff --git a/doc/examples/configure-index b/doc/examples/configure-index
index 1573eaa8b..8476d733a 100644
--- a/doc/examples/configure-index
+++ b/doc/examples/configure-index
@@ -703,6 +703,7 @@ apt::solver::upgrade "<BOOL>";
 apt::solver::remove "<BOOL>";
 apt::solver::removemanual "<BOOL>";
 apt::solver::install "<BOOL>";
+apt::solver::timeout "<INT>";
 apt::keep-downloaded-packages "<BOOL>";
 apt::solver "<STRING>";
 apt::planner "<STRING>";
-- 
cgit v1.2.3-70-g09d2