Avoid using cfunction closure (#336)

Author: metab0t

src/SQLite.jl

@@ -58,7 +58,7 @@ mutable struct DB <: DBInterface.Connection
     file::String
     handle::DBHandle
     stmt_wrappers::WeakKeyDict{StmtWrapper,Nothing} # opened prepared statements
-    registered_UDFs::Vector{Any} # keep registered UDFs alive and not garbage collected
+    registered_UDF_data::Vector{Any} # keep registered UDFs alive and not garbage collected
 
     function DB(f::AbstractString)
         handle_ptr = Ref{DBHandle}()

src/UDF.jl

@@ -44,12 +44,25 @@ end
 sqlreturn(context, val::Bool) = sqlreturn(context, Int(val))
 sqlreturn(context, val) = sqlreturn(context, sqlserialize(val))
 
+mutable struct ScalarUDFData
+    func::Function
+end
+
+mutable struct AggregateUDFData
+    init::Any
+    step::Function
+    final::Function
+end
+
 function wrap_scalarfunc(
-    func,
     context::Ptr{Cvoid},
     nargs::Cint,
     values::Ptr{Ptr{Cvoid}},
 )
+    udf_data =
+        unsafe_pointer_to_objref(C.sqlite3_user_data(context))::ScalarUDFData
+    func = udf_data.func
+
     args = [sqlvalue(values, i) for i in 1:nargs]
     ret = func(args...)
     sqlreturn(context, ret)
@@ -70,12 +83,15 @@ function bytestoint(ptr::Ptr{UInt8}, start::Int, len::Int)
 end
 
 function wrap_stepfunc(
-    init,
-    func,
     context::Ptr{Cvoid},
     nargs::Cint,
     values::Ptr{Ptr{Cvoid}},
 )
+    udf_data =
+        unsafe_pointer_to_objref(C.sqlite3_user_data(context))::AggregateUDFData
+    init = udf_data.init
+    func = udf_data.step
+
     args = [sqlvalue(values, i) for i in 1:nargs]
 
     intsize = sizeof(Int)
@@ -143,12 +159,15 @@ function wrap_stepfunc(
 end
 
 function wrap_finalfunc(
-    init,
-    func,
     context::Ptr{Cvoid},
     nargs::Cint,
     values::Ptr{Ptr{Cvoid}},
 )
+    udf_data =
+        unsafe_pointer_to_objref(C.sqlite3_user_data(context))::AggregateUDFData
+    init = udf_data.init
+    func = udf_data.final
+
     acptr = convert(Ptr{UInt8}, C.sqlite3_aggregate_context(context, 0))
 
     # step function wasn't run
@@ -201,7 +220,7 @@ Register a scalar (first method) or aggregate (second method) function
 with a [`SQLite.DB`](@ref).
 """
 function register(
-    db,
+    db::DB,
     func::Function;
     nargs::Int = -1,
     name::AbstractString = string(func),
@@ -212,11 +231,12 @@ function register(
     nargs < -1 && (nargs = -1)
     @assert sizeof(name) <= 255 "size of function name must be <= 255"
 
-    f =
-        (context, nargs, values) ->
-            wrap_scalarfunc(func, context, nargs, values)
-    cfunc = @cfunction($f, Cvoid, (Ptr{Cvoid}, Cint, Ptr{Ptr{Cvoid}}))
-    push!(db.registered_UDFs, cfunc)
+    udf_data = ScalarUDFData(func)
+    push!(db.registered_UDF_data, udf_data)
+    udf_data_ptr = pointer_from_objref(udf_data)
+
+    cfunc =
+        @cfunction(wrap_scalarfunc, Cvoid, (Ptr{Cvoid}, Cint, Ptr{Ptr{Cvoid}}))
 
     # TODO: allow the other encodings
     enc = C.SQLITE_UTF8
@@ -227,7 +247,7 @@ function register(
         name,
         nargs,
         enc,
-        C_NULL,
+        udf_data_ptr,
         cfunc,
         C_NULL,
         C_NULL,
@@ -237,7 +257,7 @@ end
 
 # as above but for aggregate functions
 function register(
-    db,
+    db::DB,
     init,
     step::Function,
     final::Function = identity;
@@ -249,16 +269,12 @@ function register(
     nargs < -1 && (nargs = -1)
     @assert sizeof(name) <= 255 "size of function name must be <= 255 chars"
 
-    s =
-        (context, nargs, values) ->
-            wrap_stepfunc(init, step, context, nargs, values)
-    cs = @cfunction($s, Cvoid, (Ptr{Cvoid}, Cint, Ptr{Ptr{Cvoid}}))
-    f =
-        (context, nargs, values) ->
-            wrap_finalfunc(init, final, context, nargs, values)
-    cf = @cfunction($f, Cvoid, (Ptr{Cvoid}, Cint, Ptr{Ptr{Cvoid}}))
-    push!(db.registered_UDFs, cs)
-    push!(db.registered_UDFs, cf)
+    udf_data = AggregateUDFData(init, step, final)
+    push!(db.registered_UDF_data, udf_data)
+    udf_data_ptr = pointer_from_objref(udf_data)
+
+    cs = @cfunction(wrap_stepfunc, Cvoid, (Ptr{Cvoid}, Cint, Ptr{Ptr{Cvoid}}))
+    cf = @cfunction(wrap_finalfunc, Cvoid, (Ptr{Cvoid}, Cint, Ptr{Ptr{Cvoid}}))
 
     enc = C.SQLITE_UTF8
     enc = isdeterm ? enc | C.SQLITE_DETERMINISTIC : enc
@@ -268,7 +284,7 @@ function register(
         name,
         nargs,
         enc,
-        C_NULL,
+        udf_data_ptr,
         C_NULL,
         cs,
         cf,