Patent Abstract:
Provided are techniques for an OS to be modified on a running system such that running programs, including system services, so not have to be stopped and restarted for the modification to take effect. The techniques include detecting, by a processing thread, when the processing thread has entered a shared library; in response to the detecting, setting a thread flag corresponding to the thread in an operating system (OS); detecting an OS flag, set by the OS, indicating that the OS is updating the shared library; in response to detecting the OS flag, suspending processing by the processing thread and transferring control from the thread to the OS; resuming processing by the processing thread in response to detecting that the OS has completed the updating; and executing the shared library in response to the resuming.

Full Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation and claims the benefit of the filing date of an application entitled, “Dynamic Library Replacement” Ser. No. 13/844,673, filed Mar. 15, 2013, assigned to the assignee of the present application, and herein incorporated by reference. 
     
    
     FIELD OF DISCLOSURE 
       [0002]    The claimed subject matter relates generally to computing systems and, more specifically, to techniques for the modification of shared libraries without shutting down associated programs. 
       BACKGROUND OF THE INVENTION 
       [0003]    Most operating systems (OSs) provide for the implementation of shared libraries, which may also be known, among other names, as shared or dynamically-linked objects. In a typical OS, shared libraries in need of a repair, or patch, are fixed by replacing one version with another. However, programs that are currently running continue to use the original rather than the replacement, or new, version and only newly executed programs access the new version. This scenario implies that a running program must be restarted to take advantage of an OS modification and, if the running program is a system service that cannot be stopped and restarted, the entire computing system must be rebooted. 
       SUMMARY 
       [0004]    Provided are techniques for an OS to be modified on a running system such that running programs, including system services, so not have to be stopped and restarted for the modification to take effect. The techniques include detecting, by a processing thread, when the processing thread has entered a shared library; in response to the detecting, setting a thread flag corresponding to the thread in an operating system (OS); detecting an OS flag, set by the OS, indicating that the OS is updating the shared library; in response to detecting the OS flag, suspending processing by the processing thread and transferring control from the thread to the OS; resuming processing by the processing thread in response to detecting that the OS has completed the updating; and executing the shared library in response to the resuming. 
         [0005]    Also provided are techniques for setting, by an operating system (OS), an OS flag indicating that the OS is updating a shared library; detecting, by the OS, that a thread flag set in response to a processing thread detecting entry into the shared library, is set; detecting that the thread flag has been cleared; replacing the shared library with an replacement shared library in response to the detecting that the thread flag has been cleared; and clearing the OS flag in response to a completion of the replacing; detecting, by a processing, thread, when the processing thread has entered a shared library; in response to the detecting, setting a thread flag corresponding to the thread in an operating system (OS); detecting an OS flag, set by the OS, indicating that the OS is updating the shared library. 
         [0006]    This summary is not intended as a comprehensive description of the claimed subject matter hut, rather, is intended to provide a brief overview of some of the functionality associated therewith. Other systems, methods, functionality, features and advantages of the claimed subject matter will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    A better understanding of the claimed subject matter can be obtained when the following detailed description of the disclosed embodiments is considered in conjunction with the following figures, in which: 
           [0008]      FIG. 1  is a block diagram of a computing system architecture that may implement the claimed subject matter. 
           [0009]      FIG. 2  is a block diagram of a computing system, first introduced in  FIG. 1 , in greater detail. 
           [0010]      FIG. 3  is a flowchart of a “Setup Library” process that may implement aspect of the claimed subject matter. 
           [0011]      FIG. 4  is a flowchart of a “Call Library” process that may implement aspect of the claimed subject matter. 
           [0012]      FIG. 5  is a flowchart of an “Update Library” process that may implement aspect of the claimed subject matter. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    As will be appreciated by one skilled in the art, aspects of the present invention may be embodied as a system, method or computer program product. Accordingly, aspects of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.” Furthermore, aspects of the present invention may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon. 
         [0014]    Any combination of one or more computer readable medium(s) may be utilized. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. 
         [0015]    A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. 
         [0016]    Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing. 
         [0017]    Computer program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The program code may execute entirely on the user&#39;s computer, partly on the user&#39;s computer, as a stand-alone software package, partly on the user&#39;s computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user&#39;s computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). 
         [0018]    Aspects of the present invention are described below with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. 
         [0019]    These computer program instructions may also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function/act specified in the flowchart and/or block diagram block or blocks. 
         [0020]    The computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational actions to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. 
         [0021]    Turning now to the figures,  FIG. 1  is a block diagram of a computing system architecture  100  that may implement the claimed subject matter. A computing system  102  includes a central processing unit (CPU)  104 , coupled to a display  106 , a keyboard  108  and a pointing device, or “mouse,”  110 , which together facilitate human interaction with elements of architecture  100  and computing system  102 . Also included in computing system  102  and attached to CPU  104  is a computer-readable storage medium (CRSM)  112 , which may either be incorporated into client system  102  i.e. an internal device, or attached externally to CPU  104  by means of various, commonly available connection devices such as but not limited to, a universal serial bus (USB) port (not shown). CRSM  112  is illustrated storing an operating system (OS)  114 , which incorporates aspects of the claimed subject matter, and an example of logic associated with a computer software program, or simply “program,”  116 . Also stored on CRSM  112  is a shared computing library, or simply “library,”  118 , i.e., a collection of computing logic incorporated and employed by other programs such as program  116 . Coupled to library  118  is a virtual application programming interface (VAN)  119 . In this example, library  118  and VAN  119  is configured in accordance with the claimed subject matter. Components  114 ,  116 ,  118  and  119  and their relationship to the claimed subject matter are described in more detail below in conjunction with  FIGS. 2-5 . 
         [0022]    Client system  102  and CPU  104  are connected to the Internet  120 , which is also connected to a server computer  122 . Although in this example, client system  102  and server  122  are communicatively coupled via the Internet  120 , they could also be coupled through any number of communication mediums such as, but not limited to, a local area network (LAN) (not shown). Further, it should be noted there are many possible configurations of computing system architectures and computing systems that may implement the claimed subject matter, of which architecture  100  and computing system  102  are only simple examples. 
         [0023]      FIG. 2  is a block diagram of computing system  102 , first introduced in  FIG. 1 , in greater detail. As shown in  FIG. 1 , computing system  102  is illustrated in the form of a general-purpose computing device. In this example, components of computing system  102  include, but are not limited to, CPU  104  ( FIG. 1 ), which may include one or more processors (not shown), a system bus  132 , which couples various components to CPU  104 , including but not limited to, input/output (I/O) interfaces  134 , a network interface card (NIC)  136  and memory  140 . In this example, NIC  136  provides a communication path between computing system  102  and the Internet  120  ( FIG. 1 ) also be provided to a LAN (not shown) or other network. I/O interfaces  134  enable various components ( FIG. 1 ) to be coupled to computing system  102  such as display  106  ( FIG. 1 ) and external devices  138 . In this example, external devices  118  include keyboard  108  ( FIG. 1 ) and mouse  110  ( FIG. 1 ). 
         [0024]    Bus  132  represents one or more of any of several types of bus structures, which for the sake of simplicity are not shown, including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, and a processor or local bus using any of a variety of bus architectures. By way of example, and not limitation, such architectures include Industry Standard Architecture (ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced. ISA (EISA) bus, Video Electronics Standards Association (VESA) local bus, and Peripheral Component interconnects (PCI) bus. 
         [0025]    Memory  140  typically includes a variety of computer system readable media. Such media may be any available media that is accessible by computer system/server  102  and includes both volatile and non-volatile media. In this example, memory  140  includes random access memory (RAM)  142  and cache memory, or simply “cache,”  144 . Computing system/ 102  and memory  140  may also further include other removable/non-removable, volatile/non-volatile computer system storage media. Memory  140  is also illustrated storing an operating system (OS)  143 , a program  145  and a shared library (SL)  146 , which includes a virtual application programming interface (VAPI)  147 . In the following examples, OS  143 , program  145  SL  146  and VAPI  147  are copies of OS  114  ( FIG. 1 ), program  116  ( FIG. 1 ), library  118  ( FIG. 1 ) and VAPI  119  ( FIG. 1 ) that are loaded into RAM  142 . St  146  is modified in accordance with the claimed, subject matter by employing features incorporated into VAN  147 . VAPI  147  and modification of SL  146  are explained in more detail below in conjunction with  FIGS. 3-5 . 
         [0026]      FIG. 3  is a flowchart of a “Setup Library” process  200  that may implement aspect of the claimed subject matter. Typically, process  200  would be implemented by a programmer or administrator that modified a typical library to function in accordance with the claimed subject matter. Process  200  starts is at “Begin Setup Library” block  202  and proceeds immediately to a “Determine Exported Functions and Data” block  204 . During processing associated with block  204 , library  118  ( FIG. 1 ) is examined to identify any functions and data that may be exported to programs such as program  116  ( FIG. 1 ). In other words, symbols associated with any non-private interfaces and data of library  118  that may be used directly by a program are identified. Typically, these identified symbols are positioned at fixed address relative to library  118 . In addition, a library routine may pass data items back to a program, or “application.” During processing associated with a “Generate Virtual Application Programming Interface (VAN)” block  206 , the fixed address of symbols in library  118  are replaced by representations in VAPI  119  ( FIG. 1 ). In other words, VAN  119  represents the exported and exposed portions of library  118  to programs such as program  116 . 
         [0027]    During processing associated with a “Rebuild Library” block  208 , library  118 , with VAPI  119  are recompiled, or “rebuilt,” and stored on CRSM  112  ( FIG. 1 ) for use by a program such as program  118 . Finally, control process to an “End Setup Library” block  219  in which process  200  is complete. 
         [0028]      FIG. 4  is a flowchart of a “Call Library” process  250  that may implement aspect of the claimed subject matter. In this example, process  250  is associated with logic of library  146  ( FIG. 2 ) that is executed on CPU  104  ( FIGS. 1 and 2 ) in conjunction with program  145  ( FIG. 2 ). Process  250  starts in a “Begin Call Library” block  252  when library  146  is called by program  145  and proceeds immediately to a “Set Thread Flag” block  254 . As explained above in conjunction with  FIG. 2 , library  146  is configured in accordance with the claimed subject matter such that program  145  calls interfaces in VAPI  147  ( FIG. 2 ) rather than interfaces in library  146 . 
         [0029]    During processing associated with block  254 , a flag (not shown) associated with library  146  is set to indicate that program  146  is about to execute code, or “enter,” library  146 . During processing associated with an “operating System OS) Flag Set” block  254 , a determination is made as to whether or not a particular flag (not shown) associated with OS  143  ( FIG. 2 ) is set (see  304 ,  FIG. 5 ). This “OS flag” is set by OS  143  when a request to update library  146  has been received by OS  143 . If the OS flag is set, control proceeds to a “Suspend Thread” block  258 . During processing associated with block  258 , a thread of program  145  that is responsible for the call to library  146  that initiated process  250  is suspended. In conjunction with the suspension, a processing table (not shown) of OS  143  is updated to reflect the suspension. 
         [0030]    During processing associated with a “Clear Thread Flag” block  260 , a flag in OS  146  that corresponds to the calling thread is cleared, indicating to OS  143  that the thread is not active, i.e., either not in the process of being called or suspended. During processing associated with a “Transfer Control to OS for Update” block  262 , control is returned to OS  143  so that library  146  can be updated. During processing associated with a. “Wait for OS to Resume Thread”  264 , the thread that called library  143  waits until OS  143  indicates that a resumption of processing is allowed, typically by changing an entry in the processing table from suspended to active. 
         [0031]    During processing associated with a “Set Thread Flag” block  266 , the thread in OS  143  is set to indicate to OS  143  that the thread is now active. Once the thread flag has been set during processing associated with block  266  or, if during processing associated with block  256 , a determination was made that the OS flag was not set, control proceeds to an “Execute Library Code” block  268 . During processing associated block  268 , the logic associated with library  143  that was called by program  145  is executed. 
         [0032]    During processing associated with a “Clear Thread Flag” block  290 , the thread flag is cleared. Finally, control proceeds to an “End Call Library” block  279  during which process  250  is complete. 
         [0033]      FIG. 5  is a flowchart of an “Update Library” process  300  that may implement aspect of the claimed subject matter. In this example, process  300  is associated with logic incorporated into OS  114  ( FIG. 1 ) and executed on one or more processors (not shown) of CPU  104  ( FIGS. 1 and 2 ) to update shared library  146  ( FIG. 2 ). In an alternative embodiment, process  300  may be incorporated into a stand-alone library update utility. 
         [0034]    Process  300  starts in a “Begin Update Library” block  302  and proceeds immediately to a “Set OS Flag” block  304 . During processing associated with block  304 , a flag (not shown) in OS  114  is set to indicate, that OS  114  is beginning the process of updating a library. During processing associated with a “Check Next Thread” block  306 , a first thread of a set of threads corresponding to a particular process (see  254 ,  260 ,  266  and  270 ,  FIG. 4 ) of a set of process threads corresponding to the library being updated, e.g. SL  146 , is checked. As explained above in conjunction with  FIG. 4 , each processing thread currently executing has a corresponding flag in OS  114  that indicates the particular thread is entering a library such as library  146 . Although described with respect to one program and one library, the claimed subject matter is equally applicable to scenarios with multiple programs and multiple libraries. In that ease, each thread of each process would have a flag for each library that may be called by the particular thread and only those threads corresponding to a library that is to be updated would be checked. 
         [0035]    During processing associated with a “Thread Sleeping” block  310 , a determination is made as to whether or not the thread being checked during processing associated with  306  is currently paused. A thread may be paused for reasons such as, but not limited to waiting for a system call to return, if a determination is made that the thread is sleeping, control proceeds to a “Wake Thread” block  312 . During processing associated with block  312 , the sleeping thread is awaken so that the thread may resume processing, eventually to complete the library call that is currently executing. Once the thread is awaken or a determination is made that the thread is not sleeping, control proceeds to a “More Threads?” block  314 . During processing associated with block  314 , as determination is made as to whether or not there are threads that still need to be checked to see if they are executing in SL  146 . If so, control returns to block  306 , the next flag corresponding to the next thread is checked and processing continues as described above. In short, process  300  continues to check the thread flags until none are set by looping through blocks  306 ,  308 ,  310 ,  312  and  314  and all the thread flags associated with the library to be updated. As explained above in conjunction with  FIG. 4 , once a thread has completed library code, the corresponding thread flag is cleared and the OS flag set during processing associated with  304  prevents the thread from reentering the library. 
         [0036]    During processing associated with an “Update Library” block  316 , SL  146  is updated. During processing associated with a “Convert Data” block  318 , any modified data or data structures associated with SL  146  are updated. During processing associated with a “Resume Threads and Clear OS Flag” block  320 , the OS flag set during processing associated with  304  is cleared and all the threads associated with SL  146  are resumed by updating the corresponding entries in the processing table. Finally, control proceeds to an “End Update Library” block  329  in which process  300  is complete. 
         [0037]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
         [0038]    The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated. 
         [0039]    The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block, diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

Technology Classification (CPC): 6