| GOLF(2gg) | Development | GOLF(2gg) |
NAME¶
write-hash - (hash)
PURPOSE¶
Store key/value pair into a hash.
SYNTAX¶
write-hash <hash> \
key <key> \
value <value> \
[ status <status> ] \
[ old-value <old value> ]
DESCRIPTION¶
write-hash will store string <key> (in "key" clause) and <value> (in "value" clause) into <hash>, which must be created with new-hash.
<key> and <value> are collectively called an "element".
If <key> already exists in the hash, then the old value associated with it is returned in string <old value> (in "old-value" clause) and <value> will replace the old value - in this case <status> number (in "status" clause) has a value of GG_INFO_EXIST.
If <key> did not exist, <status> will be GG_OKAY and <old value> is unchanged.
If a <hash> was created with "process-scope" clause (see new-hash), then the element (including <key> and <value>) will not be freed when the current request ends, rather it will persist while the process runs, unless deleted (see read-hash with delete clause).
EXAMPLES¶
Writing data to a hash:
new-hash h write-hash h key "mykey" value "some data"
Writing new value with the same key and obtaining the previous value (which is "some data"):
write-hash h key "mykey" value "new data" status st old-value od if-true st equal GG_INFO_EXIST
@Previous value for this key is <<print-out od>> end-if
The following is a key/value service, where a process-scoped hash is created. It provides inserting, deleting and querying key/value pairs. Such a service process can run indefinitely. Create file keysrv.golf:
%% /keysrv public
do-once
new-hash h hash-size 1024 process-scope
end-do-once
// Get input parameters
get-param op
get-param key
get-param data
if-true op equal "add" // Add data to hash
write-hash h key key value data old-value old_data status st
if-true st equal GG_INFO_EXIST
delete-string old_data
end-if
@Added [<<print-out key>>]
else-if op equal "delete" // Delete data and obtain the value deleted
read-hash h key (key) value val delete status st
if-true st equal GG_ERR_EXIST
@Not found [<<print-out key>>]
else-if
// If found, then delete key and value
@Deleted [<<print-out val>>]
delete-string val
end-if
else-if op equal "query" // Query hash based on key value
read-hash h key (key) value val status st
if-true st equal GG_ERR_EXIST
@Not found, queried [<<print-out key>>]
else-if
@Value [<<print-out val>>]
end-if
end-if %%
Create and make the application, then run it as service:
// Create application gg -k hash // Make application gg -q // Start application (single process key service) mgrg -w 1 hash
Try it from a command line client (see gg):
// Add data gg -r --req="/keysrv/op=add/key=15/data=15" --service --app="/hash" --exec // Query data gg -r --req="/keysrv/op=query/key=15" --service --app="/hash" --exec // Delete data gg -r --req="/keysrv/op=delete/key=15" --service --app="/hash" --exec
See read-hash for more examples.
SEE ALSO¶
Hash
get-hash new-hash purge-hash read-hash resize-hash write-hash See all documentation
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