Delivery of log records to stateless clients

A method, comprising:

• receiving, by a record delivery system from a first client in a first receiver session, a first request to read from a persistent log comprising an ordered sequence of records, wherein the first request specifies an identifier for the first receiver session but does not specify identifiers of individual ones of the records in the ordered sequence records of the persistent log to read;
• associating a data structure with the first receiver session and the persistent log, wherein the data structure indicates a pointer for a next record in the ordered sequence of records to be sent for the first receiver session;
• sending, by the record delivery system in the first receiver session to the first client based at least in part on the first request, a first set of one or more records determined according to the pointer for the next record in the ordered sequence of records indicated by the data structure for the first receiver session for which the identifier for the first receiver session was specified in the first request;
• updating, by the record delivery system for the first receiver session, the data structure for the first receiver session to move the pointer in the ordered sequence of records according to the first set of one or more records sent to the first client in the first receiver session;
• receiving, by the record delivery system from the first client in the first receiver session, a second request to read from the persistent log, wherein the second request specifies the identifier for the first receiver session but does not specify individual ones of the records in the ordered sequence of records of the persistent log to read;
• determining, by the record delivery system responsive to receipt of the second request that specifies the first receiver session identifier, a second set of one or more records that differ from the first set, according to the pointer for the next record in the ordered sequence of records indicated by the updated data structure for the first receiver session for which the identifier was specified in the second request;
• sending, by the record delivery system in the first receiver session to the first client based at least in part on the second request, the second set of one or more records;
• updating the data structure to move the pointer in the ordered sequence of records according to the second set of one or more records sent to the first client in the first receiver session;
• and
• maintaining a different data structure for a second receiver session to receive records from the persistent log according to the ordered sequence of records independent of and concurrently with the first receiver session, wherein the first receiver session and the second receiver session provide for concurrent access to the persistent log, and the different cursor for the second receiver session provides for retrieval of records to one or more other worker hosts from a different location in the ordered sequence of records of the persistent log than the cursor for the first receiver session responsive to individual ones of the one or more other worker hosts specifying an identifier of the second receiver session in a respective request without specifying individual records in the ordered sequence of records of the persistent log to retrieve.

One or more non-transitory computer-readable storage media storing program instructions that, when executed on or across one or more processors, perform:

• receiving, by a record delivery system from a first client in a first receiver session, a first request to read from a persistent log comprising an ordered sequence of records, wherein the first client comprises one or more worker threads, wherein the first request specifies an identifier for the first receiver session but does not specify identifiers of individual ones of the records in the ordered sequence of records of the persistent log to read;
• associating a cursor with the first receiver session and the persistent log, wherein the cursor indicates a pointer for a next record in the ordered sequence of records to be sent for the first receiver session;
• sending, by the record delivery system in the first receiver session to the first client as a response to the first request, a first set of one or more records determined according to the pointer for the next record in the ordered sequence of records indicated by the cursor for the first receiver session for which the identifier for the first receiver session was specified in the first request;
• updating, by the record delivery system, the cursor for the first receiver session to move the pointer in the ordered sequence of records according to the first set of one or more records sent to the first client in the first receiver session;
• receiving, by the record delivery system from the first client in the first receiver session, a second request to read from the persistent log, wherein the second request specifies the identifier for the first receiver session but does not specify individual ones of the records in the ordered sequence of records of the persistent log to read;
• determining, by the record delivery system responsive to receipt of the second request that specifies the first receiver session identifier, a second set of one or more records that differ from the first set, according to the pointer for the next record in the ordered sequence of records indicated by the updated cursor for the first receiver session for which the identifier was specified in the second request;
• sending, by the record delivery system in the first receiver session to the first client as a response to the second request, the second set of one or more records;
• updating the cursor to move the pointer in the ordered sequence of records according to the second set of one or more records sent to the first client in the first receiver session;
• and
• maintaining a different cursor for a second receiver session to receive records from the persistent log according to the ordered sequence of records independent of and concurrently with the first receiver session, wherein the first receiver session and the second receiver session provide for concurrent access to the persistent log, and the different cursor for the second receiver session provides for retrieval of records to one or more other worker hosts from a different location in the ordered sequence of records of the persistent log than the cursor for the first receiver session responsive to individual ones of the one or more other worker hosts specifying an identifier of the second receiver session in a respective request without specifying individual records in the ordered sequence of records of the persistent log to retrieve.