| Overview |  |
gen_server for the tuple space ETS table.
Copyright © (C) 2018, Fred Youhanaie
Behaviours: gen_server.
Authors: Fred Youhanaie (fyrlang@anydata.co.uk).
This is the custodian gen_server for the tuple space ETS table.
The table is created as an ordered_set and in protected
mode. All access to the table is expected to come through this
server, although other proceses can inspect the contents for
debugging purposes.
Each record has the form {Num, {Tuple}}, where Num is a unique
integer key that we initialize to 0 and increment before inserting
the next record, and Tuple is the user supplied payload. For example
if the tuple {hello, 123} is the first to be added, then the
inserted record will be {1, {hello, 123}}.
The ETS table name used will reflect the espace instance
name. This will be espace_tspace for the default/unnamed
instance, and espace_tspace_abc for an instance named abc.
etsmgr application is used to add resiliency to the server
data, should the server restart while it is holding tuple space
data.
| add_tuple/2 | Add a new tuple to the tuple space ETS table. |
| get_tuple/3 | Lookup a tuple pattern in the tuple space ETS table. |
| start_link/1 | Starts the server. |
add_tuple(Inst_name::atom(), Tuple::tuple()) -> done
Add a new tuple to the tuple space ETS table.
The tuple is inserted with a unique integer as the key, the key
is incremented with every insert.
espace_tspatt_srv
server to check for any waiting (blocking) clients whose in/rd
pattern matches the newly inserted tuple. We do not wait for any
replies from espace_tspatt_srv.
get_tuple(Inst_name::atom(), Espace_op::in | rd | inp | rdp, Pattern::tuple()) -> {nomatch} | {nomatch, reference()} | {match, {list(), tuple()}}
Lookup a tuple pattern in the tuple space ETS table.
If no match is found, {nomatch} is returned.
If a match is found, {match, Key, List, Tuple} is returned, where
Key uniquely identifies the ETS record, List is the list of the
$N elements referenced in the pattern, if any, and Tuple is the
second part of the ETS record.
This function runs within the client process. Since for rd and
rdp we do not require write access to the table, we can skip
calling the gen_server and read from the ETS table directly.
rd and rdp, although we are bypassing the gen_server, we
still need to provide some of the State data to the handler. For
now, this is created manually, but it will be fixed more elegantly
in future.
start_link(Inst_name::atom()) -> {ok, pid()} | ignore | {error, {already_started, pid()} | term()}
Starts the server.
We expect an instance name to be supplied, which will be used to uniquely identify the ETS table for the instance.Generated by EDoc