I'd like to get a list of everyone who's ever been included on any message in my inbox. Right now I can use the javax mail API to connect via IMAP and download the messages:
Folder folder = imapSslStore.getFolder("[Gmail]/All Mail");
folder.open(Folder.READ_ONLY);
Message[] messages = folder.getMessages();
for(int i = 0; i < messages.length; i++) {
// This causes the message to be lazily loaded and is slow
String[] from = messages[i].getFrom();
}
The line messages[i].getFrom() is slower than I'd like because is causes the message to be lazily loaded. Is there anything I can do to speed this up? E.g. is there some kind of bulk loading I can do instead of loading the messages one-by-one? Does this load the whole message and is there something I can do to only load the to/from/cc fields or headers instead? Would POP be any faster than IMAP?
You want to add the following before the for loop
FetchProfile fetchProfile = new FetchProfile();
fetchProfile.add(FetchProfile.Item.ENVELOPE);
folder.fetch(messages, fetchProfile);
This will prefetch the "envelope" for all the messages, which includes the from/to/subject/cc fields.
You can use fetch-method in Folder. According Javadocs:
Clients use this method to indicate that the specified items are
needed en-masse for the given message range. Implementations are
expected to retrieve these items for the given message range in a
efficient manner. Note that this method is just a hint to the
implementation to prefetch the desired items.
For fetching FROM appropriate FetchProfile is ENVELOPE. Of course it is still up to implementation and mail server does that really help.
Related
I have a scenario where I fetch some ItemBarcodes from Database. These are like this:
627729416990,627729416990,627729416990
I'm using split(",") to extract the individual items and saving it into Seq inside session.
.exec{
session =>
itemBrcdSeq = data.split(",").toSeq
session}
I want to use these items in further requests as long as there are items present.
I tried directly sending the Seq into forEach() action but it didn't work:
.foreach(itemBrcdSeq, "item"){
exec(...)
}
Please someone help where I'm doing wrong..
I'm using split(",") to extract the individual items and saving it into Seq inside session.
Your code is broken. You don't store anything in the Session, you populate a global var (and too late).
.exec { session =>
session.set("itemBrcdSeq", data.split(",").toSeq)
}.foreach("${itemBrcdSeq}", "item"){
exec(...)
}
I am looking to write a small firefox add-on that detects when files that were downloaded are (or have been) deleted locally and removes the corresponding entry in the firefox download list.
Can anybody point me to the relevant api to manipulate the download list? I cannot seem to find it.
The relevant API is PlacesUtils which abstracts the complexity of the Places database.
If your code runs in the context of a chrome window then you get a PlacesUtils glabal variable for free. Otherwise (bootstrapped, Add-on SDK, whatever) you have to import PlacesUtils.jsm.
Cu.import("resource://gre/modules/PlacesUtils.jsm");
As far as Places is concerned, downloaded files are nothing more than a special kind of visited pages, annotated accordingly. It's a matter of just one line of code to get an array of all downloaded files.
var results = PlacesUtils.annotations.getAnnotationsWithName("downloads/destinationFileURI");
Since we asked for the destinationFileURI annotation, each element of the resultarray holds the download location in the annotationValue property as a file: URI spec string.
With that you can check if the file actually exists
function getFileFromURIspec(fileurispec){
// if Services is not available in your context Cu.import("resource://gre/modules/Services.jsm");
var filehandler = Services.io.getProtocolHandler("file").QueryInterface(Ci.nsIFileProtocolHandler);
try{
return filehandler.getFileFromURLSpec(fileurispec);
}
catch(e){
return null;
}
}
getFileFromURIspec will return an instance of nsIFile, or null if the spec is invalid which shouldn't happen in this case but a sanity check never hurts. With that you can call the exists() method and if it returns false then the associated page entry in Places is eligible for removal. We can tell which is that page by its uri, which conveniently is also a property of each element of the results.
PlacesUtils.bhistory.removePage(result.uri);
To sum it up
var results = PlacesUtils.annotations.getAnnotationsWithName("downloads/destinationFileURI");
results.forEach(function(result){
var file = getFileFromURIspec(result.annotationValue);
if(!file){
// I don't know how you should treat this edge case
// ask the user, just log, remove, some combination?
}
else if(!file.exists()){
PlacesUtils.bhistory.removePage(result.uri);
}
});
Here i created a router with SmallestMailboxRouter
ActorRef actorRouter = this?.getContext()?.actorOf(new Props(RuleStandardActor.class).withRouter(new SmallestMailboxRouter(38)),"standardActorRouter")
Now in for loop i created 38 actors
for(int i=0;i <38;i++) {
ruleStandardActorRouter?.tell(new StandardActorMessage(standard: standard, responseVO: responseVO, report: report), getSelf());
}
each actor will process the logic and returns the score and message . i am receiving the message by overriding onreceive method and adding them to a list
If i run the program multiple times i am getting different scores. but it should return always same score as i am giving same input.
if (message instanceof StandardActorResponse) {
StandardActorResponse standardActorResponse = message
standardActorResponseList?.add(standardActorResponse)
}
here standardActorResponse contains message and score . if i am using same logic by just using for loop instead of akka framework i am reciving conisstant result. but in akka randomly getting different results. for example i have some rules like loginexistence and navigationexistence and alertsexistence rules. i have given one html source to these rules to check whether the html source have login,alerts,navigation links in that source. some times i am getting login doesnt exists, some times navigation doesnt exist, some times alerts doesnt exists by using akka routers and actors. but if i use for loop i am always getting same result
can any one help me to find the problem. i am using akka 2.1.4
Probably the for loop is already finished before the mailbox size is recognised. Try adding a sleep in the for loop to see the results.
I want to use amazon Dynamo DB with rails.But I have not found a way to implement pagination.
I will use AWS::Record::HashModel as ORM.
This ORM supports limits like this:
People.limit(10).each {|person| ... }
But I could not figured out how to implement following MySql query in Dynamo DB.
SELECT *
FROM `People`
LIMIT 1 , 30
You issue queries using LIMIT. If the subset returned does not contain the full table, a LastEvaluatedKey value is returned. You use this value as the ExclusiveStartKey in the next query. And so on...
From the DynamoDB Developer Guide.
You can provide 'page-size' in you query to set the result set size.
The response of DynamoDB contains 'LastEvaluatedKey' which will indicate the last key as per the page size. If response does't contain 'LastEvaluatedKey' it means there are no results left to fetch.
Use the 'LastEvaluatedKey' as 'ExclusiveStartKey' while fetching next time.
I hope this helps.
DynamoDB Pagination
Here's a simple copy-paste-run proof of concept (Node.js) for stateless forward/reverse navigation with dynamodb. In summary; each response includes the navigation history, allowing user to explicitly and consistently request either the next or previous page (while next/prev params exist):
GET /accounts -> first page
GET /accounts?next=A3r0ijKJ8 -> next page
GET /accounts?prev=R4tY69kUI -> previous page
Considerations:
If your ids are large and/or users might do a lot of navigation, then the potential size of the next/prev params might become too large.
Yes you do have to store the entire reverse path - if you only store the previous page marker (per some other answers) you will only be able to go back one page.
It won't handle changing pageSize midway, consider baking pageSize into the next/prev value.
base64 encode the next/prev values, and you could also encrypt.
Scans are inefficient, while this suited my current requirement it won't suit all!
// demo.js
const mockTable = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]
const getPagedItems = (pageSize = 5, cursor = {}) => {
// Parse cursor
const keys = cursor.next || cursor.prev || [] // fwd first
let key = keys[keys.length-1] || null // eg ddb's PK
// Mock query (mimic dynamodb response)
const Items = mockTable.slice(parseInt(key) || 0, pageSize+key)
const LastEvaluatedKey = Items[Items.length-1] < mockTable.length
? Items[Items.length-1] : null
// Build response
const res = {items:Items}
if (keys.length > 0) // add reverse nav keys (if any)
res.prev = keys.slice(0, keys.length-1)
if (LastEvaluatedKey) // add forward nav keys (if any)
res.next = [...keys, LastEvaluatedKey]
return res
}
// Run test ------------------------------------
const runTest = () => {
const PAGE_SIZE = 6
let x = {}, i = 0
// Page to end
while (i == 0 || x.next) {
x = getPagedItems(PAGE_SIZE, {next:x.next})
console.log(`Page ${++i}: `, x.items)
}
// Page back to start
while (x.prev) {
x = getPagedItems(PAGE_SIZE, {prev:x.prev})
console.log(`Page ${--i}: `, x.items)
}
}
runTest()
I faced a similar problem.
The generic pagination approach is, use "start index" or "start page" and the "page length".
The "ExclusiveStartKey" and "LastEvaluatedKey" based approach is very DynamoDB specific.
I feel this DynamoDB specific implementation of pagination should be hidden from the API client/UI.
Also in case, the application is serverless, using service like Lambda, it will be not be possible to maintain the state on the server. The other side is the client implementation will become very complex.
I came with a different approach, which I think is generic ( and not specific to DynamoDB)
When the API client specifies the start index, fetch all the keys from
the table and store it into an array.
Find out the key for the start index from the array, which is
specified by the client.
Make use of the ExclusiveStartKey and fetch the number of records, as
specified in the page length.
If the start index parameter is not present, the above steps are not
needed, we don't need to specify the ExclusiveStartKey in the scan
operation.
This solution has some drawbacks -
We will need to fetch all the keys when the user needs pagination with
start index.
We will need additional memory to store the Ids and the indexes.
Additional database scan operations ( one or multiple to fetch the
keys )
But I feel this will be very easy approach for the clients, which are using our APIs. The backward scan will work seamlessly. If the user wants to see "nth" page, this will be possible.
In fact I faced the same problem and I noticed that LastEvaluatedKey and ExclusiveStartKey are not working well especially when using Scan So I solved Like this.
GET/?page_no=1&page_size=10 =====> first page
response will contain count of records and first 10 records
retry and increase number of page until all record come.
Code is below
PS: I am using python
first_index = ((page_no-1)*page_size)
second_index = (page_no*page_size)
if (second_index > len(response['Items'])):
second_index = len(response['Items'])
return {
'statusCode': 200,
'count': response['Count'],
'response': response['Items'][first_index:second_index]
}
I'm building an nsIProtocolHandler implementation in Delphi. (more here)
And it's working already. Data the module builds gets streamed over an nsIInputStream. I've got all the nsIRequest, nsIChannel and nsIHttpChannel methods and properties working.
I've started testing and I run into something strange. I have a page "a.html" with this simple HTML:
<img src="a.png">
Both "xxm://test/a.html" and "xxm://test/a.png" work in Firefox, and give above HTML or the PNG image data.
The problem is with displaying the HTML page, the image doesn't get loaded. When I debug, I see:
NewChannel gets called for a.png, (when Firefox is processing an OnDataAvailable notice on a.html),
NotificationCallbacks is set (I only need to keep a reference, right?)
RequestHeader "Accept" is set to "image/png,image/*;q=0.8,*/*;q=0.5"
but then, the channel object is released (most probably due to a zero reference count)
Looking at other requests, I would expect some other properties to get set (such as LoadFlags or OriginalURI) and AsyncOpen to get called, from where I can start getting the request responded to.
Does anybody recognise this? Am I doing something wrong? Perhaps with LoadFlags or the LoadGroup? I'm not sure when to call AddRequest and RemoveRequest on the LoadGroup, and peeping from nsHttpChannel and nsBaseChannel I'm not sure it's better to call RemoveRequest early or late (before or after OnStartRequest or OnStopRequest)?
Update: Checked on the freshly new Firefox 3.5, still the same
Update: To try to further isolate the issue, I try "file://test/a1.html" with <img src="xxm://test/a.png" /> and still only get above sequence of events happening. If I'm supposed to add this secundary request to a load-group to get AsyncOpen called on it, I have no idea where to get a reference to it.
There's more: I find only one instance of the "Accept" string that get's added to the request headers, it queries for nsIHttpChannelInternal right after creating a new channel, but I don't even get this QueryInterface call through... (I posted it here)
Me again.
I am going to quote the same stuff from nsIChannel::asyncOpen():
If asyncOpen returns successfully, the
channel is responsible for keeping
itself alive until it has called
onStopRequest on aListener or called
onChannelRedirect.
If you go back to nsViewSourceChannel.cpp, there's one place where loadGroup->AddRequest is called and two places where loadGroup->RemoveRequest is being called.
nsViewSourceChannel::AsyncOpen(nsIStreamListener *aListener, nsISupports *ctxt)
{
NS_ENSURE_TRUE(mChannel, NS_ERROR_FAILURE);
mListener = aListener;
/*
* We want to add ourselves to the loadgroup before opening
* mChannel, since we want to make sure we're in the loadgroup
* when mChannel finishes and fires OnStopRequest()
*/
nsCOMPtr<nsILoadGroup> loadGroup;
mChannel->GetLoadGroup(getter_AddRefs(loadGroup));
if (loadGroup)
loadGroup->AddRequest(NS_STATIC_CAST(nsIViewSourceChannel*,
this), nsnull);
nsresult rv = mChannel->AsyncOpen(this, ctxt);
if (NS_FAILED(rv) && loadGroup)
loadGroup->RemoveRequest(NS_STATIC_CAST(nsIViewSourceChannel*,
this),
nsnull, rv);
if (NS_SUCCEEDED(rv)) {
mOpened = PR_TRUE;
}
return rv;
}
and
nsViewSourceChannel::OnStopRequest(nsIRequest *aRequest, nsISupports* aContext,
nsresult aStatus)
{
NS_ENSURE_TRUE(mListener, NS_ERROR_FAILURE);
if (mChannel)
{
nsCOMPtr<nsILoadGroup> loadGroup;
mChannel->GetLoadGroup(getter_AddRefs(loadGroup));
if (loadGroup)
{
loadGroup->RemoveRequest(NS_STATIC_CAST(nsIViewSourceChannel*,
this),
nsnull, aStatus);
}
}
return mListener->OnStopRequest(NS_STATIC_CAST(nsIViewSourceChannel*,
this),
aContext, aStatus);
}
Edit:
As I have no clue about how Mozilla works, so I have to guess from reading some code. From the channel's point of view, once the original file is loaded, its job is done. If you want to load the secondary items linked in file like an image, you have to implement that in the listener. See TestPageLoad.cpp. It implements a crude parser and it retrieves child items upon OnDataAvailable:
NS_IMETHODIMP
MyListener::OnDataAvailable(nsIRequest *req, nsISupports *ctxt,
nsIInputStream *stream,
PRUint32 offset, PRUint32 count)
{
//printf(">>> OnDataAvailable [count=%u]\n", count);
nsresult rv = NS_ERROR_FAILURE;
PRUint32 bytesRead=0;
char buf[1024];
if(ctxt == nsnull) {
bytesRead=0;
rv = stream->ReadSegments(streamParse, &offset, count, &bytesRead);
} else {
while (count) {
PRUint32 amount = PR_MIN(count, sizeof(buf));
rv = stream->Read(buf, amount, &bytesRead);
count -= bytesRead;
}
}
if (NS_FAILED(rv)) {
printf(">>> stream->Read failed with rv=%x\n", rv);
return rv;
}
return NS_OK;
}
The important thing is that it calls streamParse(), which looks at src attribute of img and script element, and calls auxLoad(), which creates new channel with new listener and calls AsyncOpen().
uriList->AppendElement(uri);
rv = NS_NewChannel(getter_AddRefs(chan), uri, nsnull, nsnull, callbacks);
RETURN_IF_FAILED(rv, "NS_NewChannel");
gKeepRunning++;
rv = chan->AsyncOpen(listener, myBool);
RETURN_IF_FAILED(rv, "AsyncOpen");
Since it's passing in another instance of MyListener object in there, that can also load more child items ad infinitum like a Russian doll situation.
I think I found it (myself), take a close look at this page. Why it doesn't highlight that the UUID has been changed over versions, isn't clear to me, but it would explain why things fail when (or just prior to) calling QueryInterface on nsIHttpChannelInternal.
With the new(er) UUID, I'm getting better results. As I mentioned in an update to the question, I've posted this on bugzilla.mozilla.org, I'm curious if and which response I will get there.