get()/set() improvements

* bumped version to 3.8.0
* linda:set() accepts multiple values to set in the specified slot
* linda:get() accepts an optional count to peek several values at once
* nil values are now converted just as in send()/receive()

4 files changed, 80 insertions, 70 deletions

diff --git a/src/keeper.c b/src/keeper.c
index 6d5ecbf..b0db8b4 100644
--- a/src/keeper.c
+++ b/src/keeper.c
@@ -115,11 +115,11 @@ static void fifo_push( lua_State* L, keeper_fifo* fifo, int _count)
 // expects exactly 1 value on the stack!
 // currently only called with a count of 1, but this may change in the future
 // function assumes that there is enough data in the fifo to satisfy the request
-static void fifo_peek( lua_State* L, keeper_fifo* fifo, int _count)
+static void fifo_peek( lua_State* L, keeper_fifo* fifo, int count_)
 {
         int i;
-        STACK_GROW( L, _count);
-        for( i = 0; i < _count; ++ i)
+        STACK_GROW( L, count_);
+        for( i = 0; i < count_; ++ i)
         {
                 lua_rawgeti( L, 1, fifo->first + i);
         }
@@ -384,54 +384,21 @@ int keepercall_limit( lua_State* L)
         return lua_gettop( L);
 }
 
-//in: linda_ud key [val]
+//in: linda_ud key [[val] ...]
 //out: true or nil
 int keepercall_set( lua_State* L)
 {
         bool_t should_wake_writers = FALSE;
         STACK_GROW( L, 6);
-        // make sure we have a value on the stack
-        if( lua_gettop( L) == 2)                          // ud key val?
-        {
-                lua_pushnil( L);                                // ud key nil
-        }
 
         // retrieve fifos associated with the linda
-        push_table( L, 1);                                // ud key val fifos
-        lua_replace( L, 1);                               // fifos key val
+        push_table( L, 1);                                // ud key [val [, ...]] fifos
+        lua_replace( L, 1);                               // fifos key [val [, ...]]
 
-        if( !lua_isnil( L, 3)) // set/replace contents stored at the specified key?
+        // make sure we have a value on the stack
+        if( lua_gettop( L) == 2)                          // fifos key
         {
                 keeper_fifo* fifo;
-                lua_pushvalue( L, -2);                          // fifos key val key
-                lua_rawget( L, 1);                              // fifos key val fifo|nil
-                fifo = (keeper_fifo*) lua_touserdata( L, -1);
-                if( fifo == NULL) // can be NULL if we store a value at a new key
-                {                                               // fifos key val nil
-                        lua_pop( L, 1);                               // fifos key val
-                        fifo_new( L);                                 // fifos key val fifo
-                        lua_pushvalue( L, 2);                         // fifos key val fifo key
-                        lua_pushvalue( L, -2);                        // fifos key val fifo key fifo
-                        lua_rawset( L, 1);                            // fifos key val fifo
-                }
-                else // the fifo exists, we just want to update its contents
-                {                                               // fifos key val fifo
-                        // we create room if the fifo was full but it is no longer the case
-                        should_wake_writers = (fifo->limit > 0) && (fifo->count >= fifo->limit);
-                        // empty the fifo for the specified key: replace uservalue with a virgin table, reset counters, but leave limit unchanged!
-                        lua_newtable( L);                             // fifos key val fifo {}
-                        lua_setuservalue( L, -2);                     // fifos key val fifo
-                        fifo->first = 1;
-                        fifo->count = 0;
-                }
-                fifo = prepare_fifo_access( L, -1);
-                lua_insert( L, -2);                             // fifos key fifo val
-                fifo_push( L, fifo, 1);                         // fifos key fifo
-        }
-        else // val == nil: we clear the key contents
-        {                                                 // fifos key nil
-                keeper_fifo* fifo;
-                lua_pop( L, 1);                                 // fifos key
                 lua_pushvalue( L, -1);                          // fifos key key
                 lua_rawget( L, 1);                              // fifos key fifo|nil
                 // empty the fifo for the specified key: replace uservalue with a virgin table, reset counters, but leave limit unchanged!
@@ -456,13 +423,51 @@ int keepercall_set( lua_State* L)
                         }
                 }
         }
+        else // set/replace contents stored at the specified key?
+        {
+                int count = lua_gettop( L) - 2; // number of items we want to store
+                keeper_fifo* fifo;                              // fifos key [val [, ...]]
+                lua_pushvalue( L, 2);                           // fifos key [val [, ...]] key
+                lua_rawget( L, 1);                              // fifos key [val [, ...]] fifo|nil
+                fifo = (keeper_fifo*) lua_touserdata( L, -1);
+                if( fifo == NULL) // can be NULL if we store a value at a new key
+                {                                               // fifos key [val [, ...]] nil
+                        // no need to wake writers in that case, because a writer can't wait on an inexistent key
+                        lua_pop( L, 1);                               // fifos key [val [, ...]]
+                        fifo_new( L);                                 // fifos key [val [, ...]] fifo
+                        lua_pushvalue( L, 2);                         // fifos key [val [, ...]] fifo key
+                        lua_pushvalue( L, -2);                        // fifos key [val [, ...]] fifo key fifo
+                        lua_rawset( L, 1);                            // fifos key [val [, ...]] fifo
+                }
+                else // the fifo exists, we just want to update its contents
+                {                                               // fifos key [val [, ...]] fifo
+                        // we create room if the fifo was full but it is no longer the case
+                        should_wake_writers = (fifo->limit > 0) && (fifo->count >= fifo->limit) && (count < fifo->limit);
+                        // empty the fifo for the specified key: replace uservalue with a virgin table, reset counters, but leave limit unchanged!
+                        lua_newtable( L);                             // fifos key [val [, ...]] fifo {}
+                        lua_setuservalue( L, -2);                     // fifos key [val [, ...]] fifo
+                        fifo->first = 1;
+                        fifo->count = 0;
+                }
+                fifo = prepare_fifo_access( L, -1);
+                // move the fifo below the values we want to store
+                lua_insert( L, 3);                              // fifos key fifo [val [, ...]]
+                fifo_push( L, fifo, count);                     // fifos key fifo
+        }
         return should_wake_writers ? (lua_pushboolean( L, 1), 1) : 0;
 }
 
-// in: linda_ud key
+// in: linda_ud key [count]
+// out: at most <count> values
 int keepercall_get( lua_State* L)
 {
         keeper_fifo* fifo;
+        int count = 1;
+        if( lua_gettop( L) == 3)                          // ud key count
+        {
+                count = lua_tointeger( L, 3);
+                lua_pop( L, 1);                                 // ud key
+        }
         push_table( L, 1);                                // ud key fifos
         lua_replace( L, 1);                               // fifos key
         lua_rawget( L, 1);                                // fifos fifo
@@ -470,9 +475,10 @@ int keepercall_get( lua_State* L)
         if( fifo != NULL && fifo->count > 0)
         {
                 lua_remove( L, 1);                              // fifo
-                // read one value off the fifo
-                fifo_peek( L, fifo, 1);                         // fifo ...
-                return 1;
+                count = __min( count, fifo->count);
+                // read <count> value off the fifo
+                fifo_peek( L, fifo, count);                     // fifo ...
+                return count;
         }
         // no fifo was ever registered for this key, or it is empty
         return 0;
@@ -682,16 +688,16 @@ void keeper_release( struct s_Keeper* K)
         if( K) MUTEX_UNLOCK( &K->lock_);
 }
 
-void keeper_toggle_nil_sentinels( lua_State* L, int _val_i, int _nil_to_sentinel)
+void keeper_toggle_nil_sentinels( lua_State* L, int val_i_, enum eLookupMode mode_)
 {
         int i, n = lua_gettop( L);
         /* We could use an empty table in 'keeper.lua' as the sentinel, but maybe
         * checking for a lightuserdata is faster. (any unique value will do -> take the address of some global of ours)
         */
         void* nil_sentinel = &GNbKeepers;
-        for( i = _val_i; i <= n; ++ i)
+        for( i = val_i_; i <= n; ++ i)
         {
-                if( _nil_to_sentinel)
+                if( mode_ == eLM_ToKeeper)
                 {
                         if( lua_isnil( L, i))
                         {
diff --git a/src/keeper.h b/src/keeper.h
index 2ef443d..c0fd5d0 100644
--- a/src/keeper.h
+++ b/src/keeper.h
@@ -20,7 +20,7 @@ void close_keepers( void);
 
 struct s_Keeper *keeper_acquire( const void *ptr);
 void keeper_release( struct s_Keeper *K);
-void keeper_toggle_nil_sentinels( lua_State *L, int _val_i, int _nil_to_sentinel);
+void keeper_toggle_nil_sentinels( lua_State *L, int _val_i, enum eLookupMode const mode_);
 int keeper_push_linda_storage( lua_State* L, void* ptr);
 
 typedef lua_CFunction keeper_api_t;
diff --git a/src/lanes.c b/src/lanes.c
index cad8fb1..f62c39f 100644
--- a/src/lanes.c
+++ b/src/lanes.c
@@ -52,7 +52,7 @@
  *      ...
  */
 
-char const* VERSION = "3.7.8";
+char const* VERSION = "3.8.0";
 
 /*
 ===============================================================================
@@ -464,7 +464,7 @@ LUAG_FUNC( linda_send)
         }
 
         // convert nils to some special non-nil sentinel in sent values
-        keeper_toggle_nil_sentinels( L, key_i + 1, 1);
+        keeper_toggle_nil_sentinels( L, key_i + 1, eLM_ToKeeper);
 
         STACK_GROW( L, 1);
         {
@@ -649,7 +649,7 @@ LUAG_FUNC( linda_receive)
                         {
                                 ASSERT_L( pushed >= expected_pushed_min && pushed <= expected_pushed_max);
                                 // replace sentinels with real nils
-                                keeper_toggle_nil_sentinels( L, lua_gettop( L) - pushed, 0);
+                                keeper_toggle_nil_sentinels( L, lua_gettop( L) - pushed, eLM_FromKeeper);
                                 // To be done from within the 'K' locking area
                                 //
                                 SIGNAL_ALL( &linda->read_happened);
@@ -725,28 +725,31 @@ LUAG_FUNC( linda_receive)
 
 
 /*
-* [true] = linda_set( linda_ud, key_num|str|bool|lightuserdata [,value] )
+* [true] = linda_set( linda_ud, key_num|str|bool|lightuserdata [, value [, ...]])
 *
-* Set a value to Linda.
+* Set one or more value to Linda.
 * TODO: what do we do if we set to non-nil and limit is 0?
 *
-* Existing slot value is replaced, and possible queue entries removed.
+* Existing slot value is replaced, and possible queued entries removed.
 */
 LUAG_FUNC( linda_set)
 {
-        struct s_Linda *linda = lua_toLinda( L, 1);
+        struct s_Linda* const linda = lua_toLinda( L, 1);
         int pushed;
-        bool_t has_value = !lua_isnil( L, 3);
+        bool_t has_value = lua_gettop( L) > 2;
         luaL_argcheck( L, linda, 1, "expected a linda object!");
-        luaL_argcheck( L, lua_gettop( L) <= 3, 4, "too many arguments");
 
-        // make sure the key is of a valid type
+        // make sure the key is of a valid type (throws an error if not the case)
         check_key_types( L, 2, 2);
 
         {
                 struct s_Keeper* K = keeper_acquire( linda);
                 if( K == NULL) return 0;
-                // no nil->sentinel toggling, we really clear the linda contents for the given key with a set()
+                if( has_value)
+                {
+                        // convert nils to some special non-nil sentinel in sent values
+                        keeper_toggle_nil_sentinels( L, 3, eLM_ToKeeper);
+                }
                 pushed = keeper_call( K->L, KEEPER_API( set), L, linda, 2);
                 if( pushed >= 0) // no error?
                 {
@@ -801,31 +804,32 @@ LUAG_FUNC( linda_count)
 
 
 /*
-* [val]= linda_get( linda_ud, key_num|str|bool|lightuserdata )
+* [val [, ...]] = linda_get( linda_ud, key_num|str|bool|lightuserdata [, count = 1])
 *
-* Get a value from Linda.
-* TODO: add support to get multiple values?
+* Get one or more values from Linda.
 */
 LUAG_FUNC( linda_get)
 {
-        struct s_Linda *linda= lua_toLinda( L, 1);
+        struct s_Linda* const linda = lua_toLinda( L, 1);
         int pushed;
+        int count = luaL_optint( L, 3, 1);
+        luaL_argcheck( L, count >= 1, 3, "count should be >= 1");
+        luaL_argcheck( L, linda, 1, "expected a linda object");
+        luaL_argcheck( L, lua_gettop( L) <= 3, 4, "too many arguments");
 
-        luaL_argcheck( L, linda, 1, "expected a linda object!");
-        // make sure the key is of a valid type
+        // make sure the key is of a valid type (throws an error if not the case)
         check_key_types( L, 2, 2);
-
         {
                 struct s_Keeper* K = keeper_acquire( linda);
                 if( K == NULL) return 0;
                 pushed = keeper_call( K->L, KEEPER_API( get), L, linda, 2);
-                ASSERT_L( pushed == 0 || pushed == 1);
                 if( pushed > 0)
                 {
-                        keeper_toggle_nil_sentinels( L, lua_gettop( L) - pushed, 0);
+                        keeper_toggle_nil_sentinels( L, lua_gettop( L) - pushed, eLM_FromKeeper);
                 }
                 keeper_release( K);
                 // must trigger error after keeper state has been released
+                // (an error can be raised if we attempt to read an unregistered function)
                 if( pushed < 0)
                 {
                         return luaL_error( L, "tried to copy unsupported types");
diff --git a/src/lanes.lua b/src/lanes.lua
index e7b9715..9a0287d 100644
--- a/src/lanes.lua
+++ b/src/lanes.lua
@@ -596,8 +596,8 @@ end -- settings.with_timers
 --
 -- PUBLIC LANES API
 local genlock = function( linda, key, N)
+        linda:set( key) -- clears existing data
         linda:limit( key, N)
-        linda:set( key, nil)  -- clears existing data
 
         --
         -- [true [, ...]= trues(uint)