From: Zooko O'Whielacronx Date: Wed, 24 Jan 2007 22:34:02 +0000 (-0700) Subject: update interfaces and docs for codec X-Git-Tag: tahoe_v0.1.0-0-UNSTABLE~324 X-Git-Url: https://git.rkrishnan.org/%5B/%5D%20/uri/specifications/banana.xhtml?a=commitdiff_plain;h=833ef86a8863a5fba41446aff168be88904a007f;p=tahoe-lafs%2Ftahoe-lafs.git update interfaces and docs for codec It now takes a sequence of buffers instead of a single string for both encode and decode, and it also takes a separate sequence of shareids for decode instead of a sequence of tuples, and it returns a sequence of buffers instead of a single string. --- diff --git a/pyfec/fec/fecmodule.c b/pyfec/fec/fecmodule.c index 7758ee71..9b268a40 100644 --- a/pyfec/fec/fecmodule.c +++ b/pyfec/fec/fecmodule.c @@ -85,7 +85,7 @@ Encoder_init(Encoder *self, PyObject *args, PyObject *kwdict) { static char Encoder_encode__doc__[] = "\ Encode data into m packets.\ @param inshares: a sequence of k buffers of data to encode -- these are the k primary shares, i.e. the input data split into k pieces (for best performance, make it a tuple instead of a list)\n\ -@param desired_shares_nums optional sorted sequence of sharenums indicating which shares to produce and return; If None, all m shares will be returned (in order). (For best performance, make it a tuple instead of a list.)\n\ +@param desired_shares_ids optional sorted sequence of shareids indicating which shares to produce and return; If None, all m shares will be returned (in order). (For best performance, make it a tuple instead of a list.)\n\ @returns: a list of buffers containing the requested shares\n\ "; diff --git a/src/allmydata/interfaces.py b/src/allmydata/interfaces.py index 024d7ff5..82fa569e 100644 --- a/src/allmydata/interfaces.py +++ b/src/allmydata/interfaces.py @@ -85,9 +85,9 @@ class ICodecEncoder(Interface): def get_encoder_type(): """Return a short string that describes the type of this encoder. - There must be a global table of encoder classes. This method returns - an index into this table; the value at this index is an encoder - class, and this encoder is an instance of that class. + There is required to be a global table of encoder classes. This method + returns an index into this table; the value at this index is an + encoder class, and this encoder is an instance of that class. """ def get_serialized_params(): # TODO: maybe, maybe not @@ -111,30 +111,31 @@ class ICodecEncoder(Interface): """Return the length of the shares that encode() will produce. """ - def encode(data, num_shares=None): + def encode(inshares, desired_share_ids=None): """Encode a chunk of data. This may be called multiple times. Each call is independent. - The data must be a string with a length that exactly matches the - data_size promised by set_params(). - - 'num_shares', if provided, must be equal or less than the - 'max_shares' set in set_params. If 'num_shares' is left at None, this - method will produce 'max_shares' shares. This can be used to minimize - the work that the encoder needs to do if we initially thought that we - would need, say, 100 shares, but now that it is time to actually - encode the data we only have 75 peers to send data to. - - For each call, encode() will return a Deferred that fires with a list - of 'total_shares' tuples. Each tuple is of the form (sharenum, - sharedata), where sharenum is an int (from 0 total_shares-1), and - sharedata is a string. The get_share_size() method can be used to - determine the length of the 'sharedata' strings returned by encode(). - - The (sharenum, sharedata) tuple must be kept together during storage - and retrieval. Specifically, the share data is useless by itself: the - decoder needs to be told which share is which by providing it with - both the share number and the actual share data. + The data is required to be a string with a length that exactly + matches the data_size promised by set_params(). + + 'num_shares', if provided, is required to be equal or less than the + 'max_shares' set in set_params. If 'num_shares' is left at None, + this method will produce 'max_shares' shares. This can be used to + minimize the work that the encoder needs to do if we initially + thought that we would need, say, 100 shares, but now that it is time + to actually encode the data we only have 75 peers to send data to. + + For each call, encode() will return a Deferred that fires with two + lists, one containing shares and the other containing the sharenums, + which is an int from 0 to num_shares-1. The get_share_size() method + can be used to determine the length of the 'sharedata' strings + returned by encode(). + + The sharedatas and their corresponding sharenums are required to be + kept together during storage and retrieval. Specifically, the share + data is useless by itself: the decoder needs to be told which share is + which by providing it with both the share number and the actual + share data. The memory usage of this function is expected to be on the order of total_shares * get_share_size(). @@ -161,24 +162,26 @@ class ICodecDecoder(Interface): def get_required_shares(): """Return the number of shares needed to reconstruct the data. - set_serialized_params() must be called before this.""" + set_serialized_params() is required to be called before this.""" - def decode(some_shares): + def decode(some_shares, their_shareids): """Decode a partial list of shares into data. - 'some_shares' must be a list of (sharenum, share) tuples, a subset of - the shares returned by ICodecEncode.encode(). Each share must be of - the same length. The share tuples may appear in any order, but of - course each tuple must have a sharenum that correctly matches the - associated share data string. - - This returns a Deferred which fires with a string. This string will - always have a length equal to the 'data_size' value passed into the - original ICodecEncode.set_params() call. - - The length of 'some_shares' must be equal or greater than the value - of 'required_shares' passed into the original - ICodecEncode.set_params() call. + 'some_shares' is required to be a list of buffers of sharedata, a + subset of the shares returned by ICodecEncode.encode(). Each share is + required to be of the same length. The i'th element of their_shareids + is required to be the share id (or "share num") of the i'th buffer in + some_shares. + + This returns a Deferred which fires with a sequence of buffers. This + sequence will contain all of the segments of the original data, in + order. The sum of the lengths of all of the buffers will be the + 'data_size' value passed into the original ICodecEncode.set_params() + call. + + The length of 'some_shares' is required to be exactly the value of + 'required_shares' passed into the original ICodecEncode.set_params() + call. """ class IDownloadTarget(Interface):