I am trying to store some complicated data structure with a map, and
eventually search and use it.
Since the structure can change with different applications, and it has to
work with multiple thread, I defined a generic map like follows
type IndexedMap struct {
sync.RWMutex
DataNode map[interface{}]interface{}
}
Insert is defined as
func (m *IndexedMap) Insert(dataIndex interface{}, data interface{}) error {
var err error
m.Lock()
//if the node exist
if _, ok := m.DataNode[dataIndex]; ok {
m.Unlock()
return m.Update(dataIndex, data)
} else {
//insert new node
m.DataNode[dataIndex] = data
}
m.Unlock()
return err
}
** For now, the data being inserted is a structure, not the pointer to the
structure and the key/index is a string.**
Then when I need to find a piece of data, I tried to get a snapshot of the
database first and then look for it
v, ok : = m.SnapShotData()[key] where
func (m *IndexedMap) SnapShotData() map[interface{}]interface{} {
ret := make(map[interface{}]interface{})
m.Lock()
for k, v := range m.DataNode {
ret[k] = v
}
m.Unlock()
return ret
}
Then the data v is used to do other things, never modified though.
This works but the performance is abysmal when the database getting large.
So, I tried to search without copying
v, ok := m.DataSearch(key)
func (m *IndexedMap) DataSearch(dataIndex interface{}) (interface{}, bool) {
var data interface{}
var ok bool
m.Lock()
data, ok = m.DataNode[dataIndex]
m.Unlock()
return data, ok
}
However, with this implementation, I always get crash after running the
program just a little bit with the following error
*** Error in `./colordecoder': double free or corruption (fasttop):
0x7f943c26f590 ***
SIGABRT: abort
PC=0x7f946c2eac37 m=4
signal arrived during cgo execution
I guess somewhere along the line the copy is a not a hard copy but just a
reference copy. However, I couldn't understand the difference between above
two approaches, seems that in SnapShotData I did exactly the same thing,
but no crash ever.
Can somebody tell me where I did wrong? Thanks!!
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