Erlang/OTP News feeds

by Damien Katz at March 15, 2010 07:00 PM

for
if
{tag, Reply, NewState} = method(Request, CurrentState).
tag
ok
error
gen_server
reply
no_reply
Reply
Request
NewState
CurrentState
gen_server
gen_server
init(Args)
{ok, InitialState}
handle_call(Request, From, State)
{reply, Reply, NewState}
handle_cast(Request, State)
{noreply, NewState}
terminate(Reason, State)
gen_server
gen_server:start_link(Module, Args, Options)
{ok, Pid}
Pid
gen_server:call(Pid, Request)
gen_server:cast(Pid, Request)
gen_server
eane_tcp

start(ClientHash, ClientPort) ->
   gen_server:start_link(eane_tcp_cs, [ClientHash, ClientPort], []).

gen_server

-module(eane_tcp_cs).  % The name of the module

% It implements a gen_server behaviour
-behaviour(gen_server).

% API Functions exported
-export([start/2, connect/3, hello/1, search_files/2]).

% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, terminate/2]).

% definition of the internal state
-record(tcp_state, { socket,
                    client_hash,
                    client_id,
                    port }).

% External API
% (?MODULE is a built-in macro for the name of the current module)

start(ClientHash, ClientPort) ->
   gen_server:start_link(?MODULE, [ClientHash, ClientPort], []).

hello(Pid) ->
   gen_server:cast(Pid, {hello}).

connect(Pid, Host, Port) ->
   gen_server:call(Pid, {connect, [Host, Port]}).

search_files(Pid, Query) ->
   gen_server:call(Pid, {search, Query}).

% gen_server behaviour callbacks

init(Args) ->
   [ClientHash, ClientPort] = Args,
   {ok, #tcp_state {client_hash = ClientHash, port = ClientPort}}.

handle_call({connect, [Host, Port]}, _From, TcpState) ->
   {ok, NewState} = connect_server(Host, Port, TcpState),
   {reply, ok, NewState};

handle_call({search, Name}, _From, TcpState) ->
   {ok, Reply, NewState} = send_search(Name, TcpState),
   {reply, Reply, NewState}.

handle_cast({hello}, TcpState) ->
   {ok, NewState} = send_hello(TcpState),
   {noreply, NewState}.

terminate(Reason, TcpState) ->
   close_socket(TcpState),
ok.

% Internal functions:
%   connect_server, send_search, send_hello, close_socket

linear_search(K, L) ->
    linear_search(K, L, 1).

linear_search(_, [], _) ->
    -1;
linear_search(K, [K | _], N) ->
    N;
linear_search(K, [_ | T], N) ->
    linear_search(K, T, N + 1).

timer:tc/3

perftest(N) ->
    List = rlist(N), %% Generate a list of n items
    Value = lists:max(List) + 1, %% Search for max + 1, to be in the worst case
    { BinarySearchTime, BinarySearchResult } = timer:tc(bs, search, [Value, List]),
    { LinearSearchTime, LinearSearchResult } = timer:tc(bs, linear_search, [Value, List]),
    io:format("Binary search time: ~w (~w)~n", [BinarySearchTime, BinarySearchResult]),
    io:format("Linear search time: ~w (~w)~n", [LinearSearchTime, LinearSearchResult]).

2> bs:perftest(1000000).
Binary search time: 547000 (-1)
Linear search time: 31999 (-1)
ok

fprof

profile(N) ->
    List = rlist(N),
    Value = lists:max(List) + 1,
    fprof:apply(bs, search, [Value, List]),
    fprof:profile(),
    fprof:analyse().

4> bs:profile(1000).
Reading trace data...
.........
End of trace!
Processing data...
Creating output...
%% Analysis results:
{  analysis_options,
 [{callers, true},
  {sort, acc},
  {totals, false},
  {details, true}]}.

%                                               CNT       ACC       OWN        
[{ totals,                                     9279,   33.266,   33.007}].  %%%

%                                               CNT       ACC       OWN        
[{ "0.29.0>",                                 9279,undefined,   33.007}].   %%

{[{undefined,                                     0,   33.266,    0.002}],     
 { {fprof,apply_start_stop,4},                    0,   33.266,    0.002},     %
 [{{bs,search,2},                                 1,   33.264,    0.001},      
  {suspend,                                       1,    0.000,    0.000}]}.    

{[{{fprof,apply_start_stop,4},                    1,   33.264,    0.001}],     
 { {bs,search,2},                                 1,   33.264,    0.001},     %
 [{{bs,search,4},                                 1,   33.263,    0.002}]}.    

{[{{bs,search,2},                                 1,   33.263,    0.002},      
  {{bs,search,4},                                10,    0.000,    0.019}],     
 { {bs,search,4},                                11,   33.263,    0.021},     %
 [{{lists,nth,2},                                10,   33.240,    0.010},      
  {{bs,failure,0},                                1,    0.001,    0.001},      
  {suspend,                                       1,    0.001,    0.000},      
  {{bs,search,4},                                10,    0.000,    0.019}]}.    

{[{{bs,search,4},                                10,   33.240,    0.010},      
  {{lists,nth,2},                              8996,    0.000,   32.972}],     
 { {lists,nth,2},                              9006,   33.240,   32.982},     %
 [{suspend,                                     258,    0.258,    0.000},      
  {{lists,nth,2},                              8996,    0.000,   32.972}]}.    

{[{{lists,nth,2},                               258,    0.258,    0.000},      
  {{bs,search,4},                                 1,    0.001,    0.000},      
  {{fprof,apply_start_stop,4},                    1,    0.000,    0.000}],     
 { suspend,                                     260,    0.259,    0.000},     %
 [ ]}.

{[{{bs,search,4},                                 1,    0.001,    0.001}],     
 { {bs,failure,0},                                1,    0.001,    0.001},     %
 [ ]}.

{[ ],
 { undefined,                                     0,    0.000,    0.000},     %
 [{{fprof,apply_start_stop,4},                    0,   33.266,    0.002}]}.    

Done!
ok

search/4
list:nth/2
list:nth/2

nth(1, [H|_]) -> H;
nth(N, [_|T]) when N > 1 ->
    nth(N - 1, T).

lists:nth/2

Erlang/OTP News feeds

March 15, 2010

March 11, 2010

March 08, 2010

March 06, 2010

March 03, 2010

March 02, 2010

March 01, 2010

February 25, 2010

February 24, 2010

February 20, 2010

February 19, 2010

February 16, 2010

February 12, 2010

February 10, 2010

February 09, 2010

January 18, 2010

December 16, 2009

December 15, 2009

November 03, 2009

October 29, 2009

October 23, 2009

October 13, 2009

October 07, 2009

September 29, 2009

July 06, 2009

June 17, 2009

June 03, 2009

June 02, 2009

March 17, 2009

February 25, 2009

November 12, 2008

July 12, 2008

August 16, 2007

August 13, 2007

August 12, 2007

August 10, 2007

May 19, 2007

Navigation

Erlang/OTP Projects

Documentation

Planet Trapexit

Bookmark

Personal tools

Subscriptions