add support for choosing system UCX (#37)

deps/.gitignore

@@ -0,0 +1 @@
+deps.jl

deps/build.jl

@@ -0,0 +1,45 @@
+using Libdl
+
+if haskey(ENV, "JULIA_SYSTEM_UCX")
+    @info "using system UCX"
+
+    paths = String[]
+    if haskey(ENV, "JULIA_UCX_LIBPATH")
+        push!(paths,)
+        libucp = ENV["JULIA_UCP_LIB"]
+    else
+        libucp = Libdl.find_library(["libucp"], [])
+        libucs = Libdl.find_library(["libucs"], [])
+        @debug "UCX paths" libucp libucs
+        if isempty(libucs) || isempty(libucp)
+            error("Did not find UCX libraries, please set the JULIA_UCX_LIBPATH environment variable.")
+        end
+    end
+
+    deps = quote
+        const libucp = $libucp
+        const libucs = $libucs
+    end
+else
+    deps = quote
+        import UCX_jll: libucp, libucs
+    end
+end
+
+remove_line_numbers(x) = x
+function remove_line_numbers(ex::Expr)
+    if ex.head == :macrocall
+        ex.args[2] = nothing
+    else
+        ex.args = [remove_line_numbers(arg) for arg in ex.args if !(arg isa LineNumberNode)]
+    end
+    return ex
+end
+
+# only update deps.jl if it has changed.
+# allows users to call Pkg.build("FluxRM") without triggering another round of precompilation
+deps_str = string(remove_line_numbers(deps))
+
+if !isfile("deps.jl") || deps_str != read("deps.jl", String)
+    write("deps.jl", deps_str)
+end

src/api.jl

@@ -1,5 +1,6 @@
 module API
-    using UCX_jll
+    include(joinpath(@__DIR__, "..", "deps", "deps.jl"))
+
     using CEnum
     include(joinpath("api", "ctypes.jl"))