From 8f2f4c5694ad7d6b55bf3c05d20e5b7f94419cf5 Mon Sep 17 00:00:00 2001
From: GabrielKS <23368820+GabrielKS@users.noreply.github.com>
Date: Tue, 24 Dec 2024 13:42:42 -0600
Subject: [PATCH] Add `fast_deepcopy_system` function, fix #1233

Closes #1231, closes $1233.
---
 src/PowerSystems.jl |  3 ++-
 src/base.jl         | 38 +++++++++++++++++++++++++++++++++++++-
 test/test_system.jl | 25 +++++++++++++++++++++++++
 3 files changed, 64 insertions(+), 2 deletions(-)

diff --git a/src/PowerSystems.jl b/src/PowerSystems.jl
index 103d62df3a..5445291604 100644
--- a/src/PowerSystems.jl
+++ b/src/PowerSystems.jl
@@ -605,7 +605,8 @@ import InfrastructureSystems:
     get_y_coords,
     get_raw_data_type,
     supports_time_series,
-    supports_supplemental_attributes
+    supports_supplemental_attributes,
+    fast_deepcopy_system
 import InfrastructureSystems:
     ValueCurve,
     InputOutputCurve,
diff --git a/src/base.jl b/src/base.jl
index 31d38a9f77..0218e9d7a8 100644
--- a/src/base.jl
+++ b/src/base.jl
@@ -133,7 +133,7 @@ struct System <: IS.InfrastructureSystemsType
                 "unit_system kwarg ignored. The value in SystemUnitsSetting takes precedence"
             )
         end
-        bus_numbers = Set{Int}()
+        bus_numbers = Set(get_number.(IS.get_components(ACBus, data)))
         return new(
             data,
             frequency,
@@ -2628,3 +2628,39 @@ function check_time_series_consistency(sys::System, ::Type{T}) where {T <: TimeS
 end
 
 stores_time_series_in_memory(sys::System) = IS.stores_time_series_in_memory(sys.data)
+
+"""
+Make a `deepcopy` of a [`System`](@ref) more quickly by skipping the copying of time
+series and/or supplemental attributes.
+
+# Arguments
+
+  - `data::System`: the `System` to copy
+  - `skip_time_series::Bool = true`: whether to skip copying time series
+  - `skip_supplemental_attributes::Bool = true`: whether to skip copying supplemental
+    attributes
+
+Note that setting both `skip_time_series` and `skip_supplemental_attributes` to `false`
+results in the same behavior as `deepcopy` with no performance improvement.
+"""
+function fast_deepcopy_system(
+    sys::System;
+    skip_time_series::Bool = true,
+    skip_supplemental_attributes::Bool = true,
+)
+    new_data = IS.fast_deepcopy_system(
+        sys.data;
+        skip_time_series = skip_time_series,
+        skip_supplemental_attributes = skip_supplemental_attributes,
+    )
+    new_sys = System(
+        new_data,
+        deepcopy(sys.units_settings),
+        deepcopy(sys.internal);
+        runchecks = deepcopy(sys.runchecks[]),
+        frequency = deepcopy(sys.frequency),
+        time_series_directory = deepcopy(sys.time_series_directory),
+        name = deepcopy(sys.metadata.name),
+        description = deepcopy(sys.metadata.description))
+    return new_sys
+end
diff --git a/test/test_system.jl b/test/test_system.jl
index 7e03f5f642..c1896fe398 100644
--- a/test/test_system.jl
+++ b/test/test_system.jl
@@ -399,6 +399,31 @@ end
     end
 end
 
+@testset "Test fast deepcopy of system" begin
+    systems = Dict(
+        in_memory => PSB.build_system(
+            PSITestSystems,
+            "test_RTS_GMLC_sys";
+            time_series_in_memory = in_memory,
+            force_build = true,
+        ) for in_memory in (true, false)
+    )
+    @testset for (in_memory, skip_ts, skip_sa) in  # Iterate over all permutations
+                 Iterators.product(repeat([(true, false)], 3)...)
+        sys = systems[in_memory]
+
+        sys2 = IS.fast_deepcopy_system(sys;
+            skip_time_series = skip_ts, skip_supplemental_attributes = skip_sa)
+        @test IS.compare_values(
+            sys,
+            sys2;
+            exclude = Set(
+                [:time_series_manager, :supplemental_attribute_manager][[skip_ts, skip_sa]],
+            ),
+        )
+    end
+end
+
 @testset "Test with compression enabled" begin
     @test get_compression_settings(System(100.0)) == CompressionSettings(; enabled = false)