added node limit

src/callbacks.jl

@@ -201,6 +201,10 @@ function build_bnb_callback(
                 end
             end
 
+            if iteration > tree.root.options[:node_limit]
+                tree.root.problem.solving_stage = NODE_LIMIT_REACHED
+            end
+
             fw_time = Dates.value(node.fw_time)
             fw_iter = if !isempty(fw_iterations)
                 fw_iterations[end]

src/custom_bonobo.jl

@@ -139,9 +139,9 @@ function Bonobo.get_solution(
 ) where {N,R,V,S<:FrankWolfeSolution{N,V}}
     if isempty(tree.solutions)
         @warn "There is no solution in the tree. This behaviour can happen if you have supplied 
-        \na custom domain oracle. In that case, try to increase the time limit. If you have not specified a 
+        \na custom domain oracle. In that case, try to increase the time or node limit. If you have not specified a 
         \ndomain oracle, please report!"
-        @assert tree.root.problem.solving_stage == TIME_LIMIT_REACHED
+        @assert tree.root.problem.solving_stage in (TIME_LIMIT_REACHED, NODE_LIMIT_REACHED)
         return nothing
     end
     return tree.solutions[result].solution

src/interface.jl

@@ -87,6 +87,7 @@ function solve(
     dual_gap=1e-6,
     rel_dual_gap=1.0e-2,
     time_limit=Inf,
+    node_limit=Inf,
     print_iter=100,
     dual_gap_decay_factor=0.8,
     max_fw_iter=10000,
@@ -225,6 +226,7 @@ function solve(
                 :sharpness_constant => sharpness_constant,
                 :sharpness_exponent => sharpness_exponent,
                 :time_limit => time_limit,
+                :node_limit => node_limit,
                 :usePostsolve => use_postsolve,
                 :variant => variant,
                 :use_shadow_set => use_shadow_set,
@@ -361,6 +363,8 @@ function postsolve(tree, result, time_ref, verbose, max_iteration_post)
         tree.root.problem.solving_stage = OPT_TREE_EMPTY
     elseif tree.root.problem.solving_stage == TIME_LIMIT_REACHED
         status_string = "Time limit reached"
+    elseif tree.root.problem.solving_stage == NODE_LIMIT_REACHED
+        status_string = "Node limit reached"
     else
         status_string = "Optimal (tolerance reached)"
         tree.root.problem.solving_stage = OPT_GAP_REACHED

src/problem.jl

@@ -6,6 +6,7 @@ Enum for the solving stage
     OPT_GAP_REACHED = 1
     OPT_TREE_EMPTY = 2
     TIME_LIMIT_REACHED = 3
+    NODE_LIMIT_REACHED = 4
 end
 
 """

src/utilities.jl

@@ -270,7 +270,7 @@ Checks if the branch and bound can be stopped.
 By default (in Bonobo) stops then the priority queue is empty. 
 """
 function Bonobo.terminated(tree::Bonobo.BnBTree{<:FrankWolfeNode})
-    if tree.root.problem.solving_stage == TIME_LIMIT_REACHED
+    if tree.root.problem.solving_stage in (TIME_LIMIT_REACHED, NODE_LIMIT_REACHED)
         return true
     end
     absgap = tree.incumbent - tree.lb

test/interface_test.jl

@@ -396,6 +396,12 @@ end
     @test sum(isapprox.(x_adaptive, x_monotonic, atol=1e-6, rtol=1e-3)) == n
     @test sum(isapprox.(x_agnostic, x_monotonic, atol=1e-6, rtol=1e-3)) == n
     @test sum(isapprox.(x_adaptive, x_agnostic, atol=1e-6, rtol=1e-3)) == n
+
+    x_monotonic, _, result_monotonic_node_limit =
+        Boscia.solve(f, grad!, lmo, verbose=true, line_search=line_search, node_limit=2, print_iter=1)
+
+    @test result_monotonic_node_limit[:list_ub] <= 3
+    @test result_monotonic_node_limit[:status] == "Node limit reached"
 end
 
 n = 20