Except for the Minor documentation comment below Reviewed-by: Balasubramanian Manoharan <bala.manoha...@linaro.org>
On 5 January 2017 at 20:25, Bill Fischofer <bill.fischo...@linaro.org> wrote: > Introduce three new APIs that support efficient sharing of portions of > packets. > > odp_packet_ref_static() creates an alias for a base packet > > odp_packet_ref() creates a reference to a base packet > > odp_packet_ref_pkt() creates a reference to a base packet from a supplied > header packet > > In addition, two other APIs simplify working with references > > odp_packet_is_ref() says whether a packet is a reference > > odp_packet_unshared_len() gives the sum of data lengths over all unshared > packet segments. These are the only bytes of the packet that may be > modified safely. > > Signed-off-by: Bill Fischofer <bill.fischo...@linaro.org> > --- > Changes in v6: > - Miscellaneous formatting corrections > - Minor documentation improvements > > Changes in v5: > - Clarified that both input packets to odp_packet_ref_pkt() must be from the > same pool and results are undefined if they are not. > - Clarified that input(s) to reference create APIs may be references and that > implementations are free to perform partial or full packet copies if needed > to support such compound references. > - Removed odp_packet_has_ref() and redefined odp_packet_is_ref() to indicate > simply whether other handles exist that share bytes with this packet. > - Modified validation tests to reflect the above changes. > > Changes in v4: > - Bug fixes > - Expand validation testing to cover extensions on packets with references > > Changes in v3: > - Rebased to latest API-NEXT > - Bug fixes > - Eliminate concept of base packets, both references and referenced packets > may > have head extensions as needed > include/odp/api/spec/packet.h | 172 > +++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 171 insertions(+), 1 deletion(-) > > diff --git a/include/odp/api/spec/packet.h b/include/odp/api/spec/packet.h > index 4a86eba..9b6681c 100644 > --- a/include/odp/api/spec/packet.h > +++ b/include/odp/api/spec/packet.h > @@ -256,6 +256,20 @@ uint32_t odp_packet_seg_len(odp_packet_t pkt); > uint32_t odp_packet_len(odp_packet_t pkt); > > /** > + * Packet unshared data len > + * > + * Returns the sum of data lengths over all unshared packet segments. These > + * are the only bytes that should be modified by the caller. The rest of the > + * packet should be treated as read only. odp_packet_unshared_len() will be > + * equal to odp_packet_len() if odp_packet_is_ref() is 0. > + * > + * @param pkt Packet handle > + * > + * @return Packet unshared data length > + */ > +uint32_t odp_packet_unshared_len(odp_packet_t pkt); > + > +/** > * Packet headroom length > * > * Returns the current packet level headroom length. > @@ -795,7 +809,7 @@ uint32_t odp_packet_seg_data_len(odp_packet_t pkt, > odp_packet_seg_t seg); > * data pointers. Otherwise, all old pointers remain valid. > * > * The resulting packet is always allocated from the same pool as > - * the destination packet. The source packet may have been allocate from > + * the destination packet. The source packet may have been allocated from > * any pool. > * > * On failure, both handles remain valid and packets are not modified. > @@ -848,6 +862,162 @@ int odp_packet_split(odp_packet_t *pkt, uint32_t len, > odp_packet_t *tail); > > /* > * > + * References > + * ******************************************************** > + * > + */ > + > +/** > + * Create a static reference to a packet > + * > + * A static reference is used to obtain an additional handle for referring to > + * a packet so that the storage behind it is not freed until all references > to > + * the packet are freed. This can be used, for example, to support efficient > + * retransmission processing. > + * > + * The intent of a static reference is that both the packet and the returned > + * reference to it will be treated as read only after this call. Results are > + * undefined if this restriction is not observed. > + * > + * Static references have restrictions but may have performance advantages on > + * some platforms if the caller does not intend to modify the reference > + * packet. If modification is needed (e.g., to prefix a unique header onto > the > + * packet) then odp_packet_ref() or odp_packet_ref_pkt() should be used. > + * > + * @param pkt Handle of the packet for which a static reference is > + * to be created. > + * > + * @return Handle of the static reference packet > + * @retval ODP_PACKET_INVALID Operation failed. pkt remains unchanged. > + */ > +odp_packet_t odp_packet_ref_static(odp_packet_t pkt); > + > +/** > + * Create a reference to a packet > + * > + * Create a dynamic reference to a packet starting at a specified byte > + * offset. This reference may be used as an argument to header manipulation > + * APIs to prefix a unique header onto the shared payload. The storage > + * associated with the referenced packet is not freed until all references to > + * it are freed, which permits easy multicasting or retransmission processing > + * to be performed. Following a successful call, the shared portions of the > + * referenced packet packet should be treated as read only. Results are > + * undefined if this restriction is not observed. > + * > + * This operation logically prepends a zero-length header onto the referenced > + * packet beginning at the specified offset. This header is always drawn from > + * the same pool as the referenced packet. > + * > + * Because references are unique packets, any bytes pushed onto the head of a > + * reference via odp_packet_push_head() or odp_packet_extend_head() are > unique > + * to this reference and are not seen by the referenced packet or by any > other > + * reference to the same packet. Similarly, any bytes pushed onto the > + * head of the referenced packet are not visible to any reference created > + * prior to the push operation. > + * > + * Note that the existence of references does not in any way change the > + * requirement that a single packet handle may only be manipulated by one > + * thread at a time. The odp_packet_unshared_len() API may be used to > + * determine the number of bytes starting at offset zero that are unique to > + * this packet handle. Only these bytes should be considered modifiable. All > + * other bytes accessible from this handle should be treated as read only. > + * > + * The packet used as input to this routine may itself by a reference to some > + * other packet. Implementations that are unable to support such compound > + * references without copies MAY perform a partial or full packet copy > + * operation to return a valid reference in response to this call. > + * > + * If the caller does not indend to push a header onto either the returned > + * reference or the packet being referenced, or otherwise modify either > + * packet, the odp_packet_ref_static() API may be used. This may be a more > + * efficient means of obtaining another reference to a packet if both will be > + * treated as read only. > + * > + * @param pkt Handle of the packet for which a reference is to be > + * created. > + * > + * @param offset Byte offset in pkt at which the shared reference is to > + * begin. This must be in the range 0..odp_packet_len(pkt)-1. > + * > + * @return Handle of the reference packet > + * @retval ODP_PACKET_INVALID Operation failed. pkt remains unchanged. > + */ > +odp_packet_t odp_packet_ref(odp_packet_t pkt, uint32_t offset); > + > +/** > + * Create a reference to another packet from a header packet > + * > + * Create a dynamic reference to a packet starting at a specified byte offset > + * by prepending a supplied header packet. The resulting reference consists > of > + * the unshared header followed by the shared referenced packet starting at > + * the specified offset. This shared portion should be regarded as read > + * only. The storage associated with the shared portion of the reference is > + * not freed until all references to it are freed, which permits easy > + * multicasting or retransmission processing to be performed. > + * > + * Because references are unique packets, any bytes pushed onto the head of a > + * reference via odp_packet_push_head() or odp_packet_extend_head() are > unique > + * to this reference and are not seen by the referenced packet or by any > other > + * reference to the same packet. Similarly, any bytes pushed onto the > + * head of the referenced packet are not visible to any reference created > + * prior to the push operation. > + * > + * Note that the existence of references does not in any way change the > + * requirement that a single packet handle may only be manipulated by one > + * thread at a time. The odp_packet_unshared_len() API may be used to > + * determine the number of bytes starting at offset zero that are unique to > + * this packet handle. Only these bytes should be considered modifiable. All > + * other bytes accessible from this handle should be treated as read only. > + * > + * Either packet used as input to this routine may itself by a reference to > + * some other packet. Implementations that are unable to support such > compound > + * references without copies MAY perform a partial or full packet copy > + * operation to return a valid reference in response to this call. > + * > + * The packets used as input to this routine should be drawn from the same > + * pool. Results are undefined if this restriction is not observed. > + * > + * odp_packet_pool() on the returned reference returns the pool id of the > + * header packet. > + * > + * @param pkt Handle of the packet for which a reference is to be > + * created. > + * > + * @param offset Byte offset in pkt at which the shared reference is to > + * begin. Must be in the range 0..odp_packet_len(pkt)-1. > + * > + * @param hdr Handle of the header packet to be prefixed onto pkt to > create > + * the reference. If this is specified as ODP_PACKET_INVALID, > + * this call is equivalent to odp_packet_ref(). The supplied > hdr > + * must be distinct from pkt and results are undefined if an > + * attempt is made to create circular references. We can add documentation that if 'hdr' or 'pkt' is ODP_PACKET_INVALID then then api will fail. > + * > + * @return Handle of the reference packet. This may or may not be the > + * same as the input hdr packet. The caller should only use > this > + * handle since the original hdr packet no longer has any > + * independent existence. > + * > + * @retval ODP_PACKET_INVALID Operation failed. Both pkt and hdr are > unchanged. > + */ > +odp_packet_t odp_packet_ref_pkt(odp_packet_t pkt, uint32_t offset, > + odp_packet_t hdr); > + > +/** > + * Test if a packet is a reference > + * > + * A packet is a reference if any other packet handles exist that share any > + * data bytes with this packet. > + * > + * @param pkt Packet handle > + * > + * @retval 0 Packet is not a reference. All bytes in this packet are > unshared. > + * @retval 1 Packet is a reference. One or more other packet handles exist > + * that share bytes with this packet. > + */ > +int odp_packet_is_ref(odp_packet_t pkt); > + > +/* > + * > * Copy > * ******************************************************** > * > -- > 2.7.4 >
