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May 4, 2017 08:50
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| %% Based on code from | |
| %% Erlang Programming | |
| %% Francecso Cesarini and Simon Thompson | |
| %% O'Reilly, 2008 | |
| %% http://oreilly.com/catalog/9780596518189/ | |
| %% http://www.erlangprogramming.org/ | |
| %% (c) Francesco Cesarini and Simon Thompson | |
| -module(gf). | |
| -behaviour(gen_server). | |
| % an implementation of this is included. | |
| -export([start_link/0]). | |
| % you need to implement these functions. | |
| -export([init/1, handle_call/3, handle_cast/2]). | |
| % these are implemented for you. | |
| -export([handle_info/2, terminate/2, code_change/3]). | |
| % you will need to implement these. | |
| -export([allocate/0,deallocate/1,stop/0]). | |
| -export([run_simulation/0]). | |
| %% These are the start functions used to create and | |
| %% initialize the server. | |
| start_link() -> | |
| gen_server:start_link( | |
| {local, ?MODULE}, | |
| ?MODULE, [], []). | |
| init([]) -> | |
| Frequencies = {get_frequencies(), []}, | |
| {ok, Frequencies}. | |
| % Hard Coded | |
| get_frequencies() -> [10,11,12,13,14,15]. | |
| %% Functional interface | |
| allocate() -> | |
| gen_server:call(?MODULE, allocate). | |
| deallocate(Freq) -> | |
| gen_server:cast(?MODULE, {deallocate, Freq}). | |
| report() -> | |
| gen_server:call(?MODULE, report). | |
| add(Freqs) -> | |
| gen_server:call(?MODULE, {add, Freqs}). | |
| stop() -> | |
| gen_server:stop(?MODULE). | |
| handle_call(allocate, From, State) -> | |
| {NewState, Reply} = allocate(State, From), | |
| {reply, Reply, NewState}; | |
| handle_call(report, _From, State) -> | |
| {Free, Allocated} = State, | |
| FreeNum = length(Free), | |
| AllocatedNum = length(Allocated), | |
| {reply, {{'Free', FreeNum}, {'Allocated', AllocatedNum}}, State}; | |
| handle_call({add, []}, _From, State) -> | |
| {reply, error, State}; | |
| handle_call({add, NewFreqs}, _From, State) -> | |
| {Free, Allocated} = State, | |
| SortedFree = lists:usort(Free), | |
| SortedNewFreqs = lists:usort(NewFreqs), | |
| SortedNewFree = lists:umerge(SortedNewFreqs, SortedFree), | |
| FreeHasNoDuplicates = length(SortedFree) == length(Free), | |
| NewFreqsHasNoDuplicates = length(SortedNewFreqs) == length(NewFreqs), | |
| NewFreeHasNoDuplicates = length(SortedNewFree) == length(SortedNewFreqs ++ SortedFree), | |
| if | |
| FreeHasNoDuplicates andalso NewFreqsHasNoDuplicates andalso NewFreeHasNoDuplicates -> | |
| {reply, ok, {SortedNewFree, Allocated}}; | |
| true -> | |
| {reply, error, State} | |
| end. | |
| handle_cast({deallocate, Freq}, State) -> | |
| NewState = deallocate(State, Freq), | |
| {noreply, NewState}. | |
| %% The Internal Help Functions used to allocate and | |
| %% deallocate frequencies. | |
| allocate({[], Allocated}, _Pid) -> | |
| {{[], Allocated}, {error, no_frequency}}; | |
| allocate({[Freq|Free], Allocated}, Pid) -> | |
| {{Free, [{Freq, Pid}|Allocated]}, {ok, Freq}}. | |
| deallocate({Free, Allocated}, Freq) -> | |
| NewAllocated=lists:keydelete(Freq, 1, Allocated), | |
| {[Freq|Free], NewAllocated}. | |
| % default implementations | |
| handle_info(_Info, State) -> | |
| {noreply, State}. | |
| terminate(_Reason, _State) -> | |
| ok. | |
| code_change(_OldVsn, State, _Extra) -> | |
| {ok, State}. | |
| run_simulation() -> | |
| S1 = start_link(), | |
| io:format("Start: ~p~n", [S1]), | |
| io:format("Report: ~p~n", [report()]), | |
| timer:sleep(1000), | |
| S2 = allocate(), | |
| io:format("Allocate: ~p~n", [S2]), | |
| io:format("Report: ~p~n", [report()]), | |
| timer:sleep(1000), | |
| S3 = allocate(), | |
| io:format("Allocate: ~p~n", [S3]), | |
| io:format("Report: ~p~n", [report()]), | |
| timer:sleep(1000), | |
| S4 = allocate(), | |
| io:format("Allocate: ~p~n", [S4]), | |
| io:format("Report: ~p~n", [report()]), | |
| timer:sleep(1000), | |
| S5 = deallocate(11), | |
| io:format("Deallocate (11): ~p~n", [S5]), | |
| io:format("Report: ~p~n", [report()]), | |
| timer:sleep(1000), | |
| S6 = allocate(), | |
| io:format("Allocate: ~p~n", [S6]), | |
| io:format("Report: ~p~n", [report()]), | |
| timer:sleep(1000), | |
| S7 = add([]), | |
| io:format("Add []: ~p~n", [S7]), | |
| io:format("Report: ~p~n", [report()]), | |
| timer:sleep(1000), | |
| NewFreqs = [20,21,22], | |
| S8 = add(NewFreqs), | |
| io:format("Add ~p: ~p~n", [NewFreqs, S8]), | |
| io:format("Report: ~p~n", [report()]), | |
| timer:sleep(1000), | |
| S9 = stop(), | |
| io:format("Stop: ~p~n", [S9]). | |
| % c(gf). | |
| % gf:run_simulation(). |
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