From eb0478b682e6dd3ca3eccea34af1322d1873a129 Mon Sep 17 00:00:00 2001
From: Joshua Lampert <51029046+JoshuaLampert@users.noreply.github.com>
Date: Tue, 21 Nov 2023 07:29:13 +0100
Subject: [PATCH] Initialize p4est and t8code only if possible (#1745)

* initialize p4est and t8code only if possible

* format

* add warning if p4est/t8code are not usable
---
 Project.toml            |  4 +--
 src/auxiliary/p4est.jl  | 18 ++++++++-----
 src/auxiliary/t8code.jl | 56 +++++++++++++++++++++++------------------
 3 files changed, 45 insertions(+), 33 deletions(-)

diff --git a/Project.toml b/Project.toml
index 17c02a2adac..4b7b69af93b 100644
--- a/Project.toml
+++ b/Project.toml
@@ -66,7 +66,7 @@ Makie = "0.19"
 MuladdMacro = "0.2.2"
 Octavian = "0.3.5"
 OffsetArrays = "1.3"
-P4est = "0.4"
+P4est = "0.4.9"
 Polyester = "0.7.5"
 PrecompileTools = "1.1"
 Printf = "1"
@@ -84,7 +84,7 @@ StaticArrays = "1"
 StrideArrays = "0.1.18"
 StructArrays = "0.6"
 SummationByPartsOperators = "0.5.41"
-T8code = "0.4.1"
+T8code = "0.4.3"
 TimerOutputs = "0.5"
 Triangulate = "2.0"
 TriplotBase = "0.1"
diff --git a/src/auxiliary/p4est.jl b/src/auxiliary/p4est.jl
index 968af339cbd..0b826254129 100644
--- a/src/auxiliary/p4est.jl
+++ b/src/auxiliary/p4est.jl
@@ -13,14 +13,20 @@ This function will check if `p4est` is already initialized
 and if yes, do nothing, thus it is safe to call it multiple times.
 """
 function init_p4est()
-    p4est_package_id = P4est.package_id()
-    if p4est_package_id >= 0
-        return nothing
+    # Only initialize p4est if P4est.jl can be used
+    if P4est.preferences_set_correctly()
+        p4est_package_id = P4est.package_id()
+        if p4est_package_id >= 0
+            return nothing
+        end
+
+        # Initialize `p4est` with log level ERROR to prevent a lot of output in AMR simulations
+        p4est_init(C_NULL, SC_LP_ERROR)
+    else
+        @warn "Preferences for P4est.jl are not set correctly. Until fixed, using `P4estMesh` will result in a crash. " *
+              "See also https://trixi-framework.github.io/Trixi.jl/stable/parallelization/#parallel_system_MPI"
     end
 
-    # Initialize `p4est` with log level ERROR to prevent a lot of output in AMR simulations
-    p4est_init(C_NULL, SC_LP_ERROR)
-
     return nothing
 end
 
diff --git a/src/auxiliary/t8code.jl b/src/auxiliary/t8code.jl
index 37cb782bb93..bd781b21c1e 100644
--- a/src/auxiliary/t8code.jl
+++ b/src/auxiliary/t8code.jl
@@ -7,34 +7,40 @@ is already initialized and if yes, do nothing, thus it is safe to call it
 multiple times.
 """
 function init_t8code()
-    t8code_package_id = t8_get_package_id()
-    if t8code_package_id >= 0
-        return nothing
-    end
+    # Only initialize t8code if T8code.jl can be used
+    if T8code.preferences_set_correctly()
+        t8code_package_id = t8_get_package_id()
+        if t8code_package_id >= 0
+            return nothing
+        end
 
-    # Initialize the sc library, has to happen before we initialize t8code.
-    let catch_signals = 0, print_backtrace = 0, log_handler = C_NULL
-        T8code.Libt8.sc_init(mpi_comm(), catch_signals, print_backtrace, log_handler,
-                             T8code.Libt8.SC_LP_ERROR)
-    end
+        # Initialize the sc library, has to happen before we initialize t8code.
+        let catch_signals = 0, print_backtrace = 0, log_handler = C_NULL
+            T8code.Libt8.sc_init(mpi_comm(), catch_signals, print_backtrace, log_handler,
+                                 T8code.Libt8.SC_LP_ERROR)
+        end
 
-    if T8code.Libt8.p4est_is_initialized() == 0
-        # Initialize `p4est` with log level ERROR to prevent a lot of output in AMR simulations
-        T8code.Libt8.p4est_init(C_NULL, T8code.Libt8.SC_LP_ERROR)
-    end
+        if T8code.Libt8.p4est_is_initialized() == 0
+            # Initialize `p4est` with log level ERROR to prevent a lot of output in AMR simulations
+            T8code.Libt8.p4est_init(C_NULL, T8code.Libt8.SC_LP_ERROR)
+        end
 
-    # Initialize t8code with log level ERROR to prevent a lot of output in AMR simulations.
-    t8_init(T8code.Libt8.SC_LP_ERROR)
-
-    if haskey(ENV, "TRIXI_T8CODE_SC_FINALIZE")
-        # Normally, `sc_finalize` should always be called during shutdown of an
-        # application. It checks whether there is still un-freed memory by t8code
-        # and/or T8code.jl and throws an exception if this is the case. For
-        # production runs this is not mandatory, but is helpful during
-        # development. Hence, this option is only activated when environment
-        # variable TRIXI_T8CODE_SC_FINALIZE exists.
-        @warn "T8code.jl: sc_finalize will be called during shutdown of Trixi.jl."
-        MPI.add_finalize_hook!(T8code.Libt8.sc_finalize)
+        # Initialize t8code with log level ERROR to prevent a lot of output in AMR simulations.
+        t8_init(T8code.Libt8.SC_LP_ERROR)
+
+        if haskey(ENV, "TRIXI_T8CODE_SC_FINALIZE")
+            # Normally, `sc_finalize` should always be called during shutdown of an
+            # application. It checks whether there is still un-freed memory by t8code
+            # and/or T8code.jl and throws an exception if this is the case. For
+            # production runs this is not mandatory, but is helpful during
+            # development. Hence, this option is only activated when environment
+            # variable TRIXI_T8CODE_SC_FINALIZE exists.
+            @warn "T8code.jl: sc_finalize will be called during shutdown of Trixi.jl."
+            MPI.add_finalize_hook!(T8code.Libt8.sc_finalize)
+        end
+    else
+        @warn "Preferences for T8code.jl are not set correctly. Until fixed, using `T8codeMesh` will result in a crash. " *
+              "See also https://trixi-framework.github.io/Trixi.jl/stable/parallelization/#parallel_system_MPI"
     end
 
     return nothing