These traces were collected as part of the study reported in "Demystifying
Cache Policies for Photo Stores at Scale: A Tencent Case Study" by Ke Zhou
et al., published in ICS 2018, DOI 10.1145/3205289.3205299.

The traces are in text format, with fields separated with blanks.
Here is a sample line:

20160201164604 085abb02a06850729bb01479466420d9e102d325 5 m 12903 1 PHONE 1
             ^                                        ^ ^ ^     ^ ^     ^ ^
timestamp----+                                        | | |     | |     | |
photo ID (checksum)-----------------------------------+ | |     | |     | |
image format (0 = jpg, 5 = web)-------------------------+ |     | |     | |
size specification (l, a, o, m, c, b)---------------------+     | |     | |
return size (bytes)---------------------------------------------+ |     | |
cache hit (1) or miss (0)-----------------------------------------+     | |
terminal type (PHONE or PC)---------------------------------------------+ |
response time (ms; 0 means < 1ms)-----------------------------------------+

The timestamp is in YYYYMMDDHHMMSS format.

Records that have an image format other than 0 or 5 indicate errors
and should be discarded.

The size specification is l, a, o, m, c, or b, corresponding to increasing
size categories, with the largest return size observed for each category
as follows:

        l    33,136
        a 3,263,749
        o 4,925,317
        m 6,043,467
        c 6,050,183
        b 8,387,821