prosody
34ac05f6bd10
util-src/managed_pointer.h

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util-src/managed_pointer.h @ 13744:34ac05f6bd10 13.0

core.configmanager: Fix reporting delayed warnings from global section A Credential in the global section would be stored at delayed_warnings["*/secret"], but get("example.com","secret") would look for delayed_warnings["example.com/secret"] Storing the warnings in the config itself has the unfortunate side-effect that the config now contains util.error objects, which may be awkward if something bypasses get(). Should rawget() also do this filtering? getconfig() too? Currently this only affects prosodyctl, so maybe it won't be much of a problem.
author Kim Alvefur <zash@zash.se>
date Sat, 22 Feb 2025 00:08:18 +0100
parent 12692:b001b0f42512
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1 /* managed_pointer.h
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2
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3 These macros allow wrapping an allocator/deallocator into an object that is
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4 owned and managed by the Lua garbage collector.
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5
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6 Why? It is too easy to leak objects that need to be manually released, especially
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7 when dealing with the Lua API which can throw errors from many operations.
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8
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9 USAGE
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10 -----
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11
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12 For example, given an object that can be created or released with the following
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13 functions:
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14
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15 fancy_buffer* new_buffer();
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16 void free_buffer(fancy_buffer* p_buffer)
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17
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18 You could declare a managed version like so:
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19
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20 MANAGED_POINTER_ALLOCATOR(new_managed_buffer, fancy_buffer*, new_buffer, free_buffer)
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21
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22 And then, when you need to create a new fancy_buffer in your code:
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23
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24 fancy_buffer *my_buffer = new_managed_buffer(L);
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25
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26 NOTES
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27 -----
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28
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29 Managed objects MUST NOT be freed manually. They will automatically be
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30 freed during the next GC sweep after your function exits (even if via an error).
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31
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32 The managed object is pushed onto the stack, but should generally be ignored,
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33 but you'll need to bear this in mind when creating managed pointers in the
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34 middle of a sequence of stack operations.
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35 */
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36
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37 #define MANAGED_POINTER_MT(wrapped_type) #wrapped_type "_managedptr_mt"
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38
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39 #define MANAGED_POINTER_ALLOCATOR(name, wrapped_type, wrapped_alloc, wrapped_free) \
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40 static int _release_ ## name(lua_State *L) { \
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41 wrapped_type *p = (wrapped_type*)lua_topointer(L, 1); \
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42 if(*p != NULL) { \
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43 wrapped_free(*p); \
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44 } \
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45 return 0; \
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46 } \
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47 static wrapped_type name(lua_State *L) { \
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48 wrapped_type *p = (wrapped_type*)lua_newuserdata(L, sizeof(wrapped_type)); \
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49 if(luaL_newmetatable(L, MANAGED_POINTER_MT(wrapped_type)) != 0) { \
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50 lua_pushcfunction(L, _release_ ## name); \
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51 lua_setfield(L, -2, "__gc"); \
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52 } \
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53 lua_setmetatable(L, -2); \
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54 *p = wrapped_alloc(); \
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55 if(*p == NULL) { \
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56 lua_pushliteral(L, "not enough memory"); \
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57 lua_error(L); \
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58 } \
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59 return *p; \
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60 }
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